compiling various versions of Python, which toolchain?

[Larz60+]

You should use pyenv if you need many versions of python. The list is exhaustive see below:
Pyenv available versions:

$ pyenv install --list
Available versions:
  2.1.3
  2.2.3
  2.3.7
  2.4.0
  2.4.1
  2.4.2
  2.4.3
  2.4.4
  2.4.5
  2.4.6
  2.5.0
  2.5.1
  2.5.2
  2.5.3
  2.5.4
  2.5.5
  2.5.6
  2.6.6
  2.6.7
  2.6.8
  2.6.9
  2.7.0
  2.7-dev
  2.7.1
  2.7.2
  2.7.3
  2.7.4
  2.7.5
  2.7.6
  2.7.7
  2.7.8
  2.7.9
  2.7.10
  2.7.11
  2.7.12
  2.7.13
  2.7.14
  2.7.15
  2.7.16
  3.0.1
  3.1.0
  3.1.1
  3.1.2
  3.1.3
  3.1.4
  3.1.5
  3.2.0
  3.2.1
  3.2.2
  3.2.3
  3.2.4
  3.2.5
  3.2.6
  3.3.0
  3.3.1
  3.3.2
  3.3.3
  3.3.4
  3.3.5
  3.3.6
  3.3.7
  3.4.0
  3.4-dev
  3.4.1
  3.4.2
  3.4.3
  3.4.4
  3.4.5
  3.4.6
  3.4.7
  3.4.8
  3.4.9
  3.4.10
  3.5.0
  3.5-dev
  3.5.1
  3.5.2
  3.5.3
  3.5.4
  3.5.5
  3.5.6
  3.5.7
  3.6.0
  3.6-dev
  3.6.1
  3.6.2
  3.6.3
  3.6.4
  3.6.5
  3.6.6
  3.6.7
  3.6.8
  3.7.0
  3.7-dev
  3.7.1
  3.7.2
  3.7.3
  3.8-dev
  activepython-2.7.14
  activepython-3.5.4
  activepython-3.6.0
  anaconda-1.4.0
  anaconda-1.5.0
  anaconda-1.5.1
  anaconda-1.6.0
  anaconda-1.6.1
  anaconda-1.7.0
  anaconda-1.8.0
  anaconda-1.9.0
  anaconda-1.9.1
  anaconda-1.9.2
  anaconda-2.0.0
  anaconda-2.0.1
  anaconda-2.1.0
  anaconda-2.2.0
  anaconda-2.3.0
  anaconda-2.4.0
  anaconda-4.0.0
  anaconda2-2.4.0
  anaconda2-2.4.1
  anaconda2-2.5.0
  anaconda2-4.0.0
  anaconda2-4.1.0
  anaconda2-4.1.1
  anaconda2-4.2.0
  anaconda2-4.3.0
  anaconda2-4.3.1
  anaconda2-4.4.0
  anaconda2-5.0.0
  anaconda2-5.0.1
  anaconda2-5.1.0
  anaconda2-5.2.0
  anaconda2-5.3.0
  anaconda2-5.3.1
  anaconda2-2018.12
  anaconda2-2019.03
  anaconda3-2.0.0
  anaconda3-2.0.1
  anaconda3-2.1.0
  anaconda3-2.2.0
  anaconda3-2.3.0
  anaconda3-2.4.0
  anaconda3-2.4.1
  anaconda3-2.5.0
  anaconda3-4.0.0
  anaconda3-4.1.0
  anaconda3-4.1.1
  anaconda3-4.2.0
  anaconda3-4.3.0
  anaconda3-4.3.1
  anaconda3-4.4.0
  anaconda3-5.0.0
  anaconda3-5.0.1
  anaconda3-5.1.0
  anaconda3-5.2.0
  anaconda3-5.3.0
  anaconda3-5.3.1
  anaconda3-2018.12
  anaconda3-2019.03
  ironpython-dev
  ironpython-2.7.4
  ironpython-2.7.5
  ironpython-2.7.6.3
  ironpython-2.7.7
  jython-dev
  jython-2.5.0
  jython-2.5-dev
  jython-2.5.1
  jython-2.5.2
  jython-2.5.3
  jython-2.5.4-rc1
  jython-2.7.0
  jython-2.7.1
  micropython-dev
  micropython-1.9.3
  micropython-1.9.4
  micropython-1.10
  miniconda-latest
  miniconda-2.2.2
  miniconda-3.0.0
  miniconda-3.0.4
  miniconda-3.0.5
  miniconda-3.3.0
  miniconda-3.4.2
  miniconda-3.7.0
  miniconda-3.8.3
  miniconda-3.9.1
  miniconda-3.10.1
  miniconda-3.16.0
  miniconda-3.18.3
  miniconda2-latest
  miniconda2-3.18.3
  miniconda2-3.19.0
  miniconda2-4.0.5
  miniconda2-4.1.11
  miniconda2-4.3.14
  miniconda2-4.3.21
  miniconda2-4.3.27
  miniconda2-4.3.30
  miniconda3-latest
  miniconda3-2.2.2
  miniconda3-3.0.0
  miniconda3-3.0.4
  miniconda3-3.0.5
  miniconda3-3.3.0
  miniconda3-3.4.2
  miniconda3-3.7.0
  miniconda3-3.8.3
  miniconda3-3.9.1
  miniconda3-3.10.1
  miniconda3-3.16.0
  miniconda3-3.18.3
  miniconda3-3.19.0
  miniconda3-4.0.5
  miniconda3-4.1.11
  miniconda3-4.2.12
  miniconda3-4.3.11
  miniconda3-4.3.14
  miniconda3-4.3.21
  miniconda3-4.3.27
  miniconda3-4.3.30
  pypy-c-jit-latest
  pypy-c-nojit-latest
  pypy-dev
  pypy-stm-2.3
  pypy-stm-2.5.1
  pypy-1.5-src
  pypy-1.5
  pypy-1.6
  pypy-1.7
  pypy-1.8
  pypy-1.9
  pypy-2.0-src
  pypy-2.0
  pypy-2.0.1-src
  pypy-2.0.1
  pypy-2.0.2-src
  pypy-2.0.2
  pypy-2.1-src
  pypy-2.1
  pypy-2.2-src
  pypy-2.2
  pypy-2.2.1-src
  pypy-2.2.1
  pypy-2.3-src
  pypy-2.3
  pypy-2.3.1-src
  pypy-2.3.1
  pypy-2.4.0-src
  pypy-2.4.0
  pypy-2.5.0-src
  pypy-2.5.0
  pypy-2.5.1-src
  pypy-2.5.1
  pypy-2.6.0-src
  pypy-2.6.0
  pypy-2.6.1-src
  pypy-2.6.1
  pypy-4.0.0-src
  pypy-4.0.0
  pypy-4.0.1-src
  pypy-4.0.1
  pypy-5.0.0-src
  pypy-5.0.0
  pypy-5.0.1-src
  pypy-5.0.1
  pypy-5.1-src
  pypy-5.1
  pypy-5.1.1-src
  pypy-5.1.1
  pypy-5.3-src
  pypy-5.3
  pypy-5.3.1-src
  pypy-5.3.1
  pypy-5.4-src
  pypy-5.4
  pypy-5.4.1-src
  pypy-5.4.1
  pypy-5.6.0-src
  pypy-5.6.0
  pypy-5.7.0-src
  pypy-5.7.0
  pypy-5.7.1-src
  pypy-5.7.1
  pypy2-5.3-src
  pypy2-5.3
  pypy2-5.3.1-src
  pypy2-5.3.1
  pypy2-5.4-src
  pypy2-5.4
  pypy2-5.4.1-src
  pypy2-5.4.1
  pypy2-5.6.0-src
  pypy2-5.6.0
  pypy2-5.7.0-src
  pypy2-5.7.0
  pypy2-5.7.1-src
  pypy2-5.7.1
  pypy2.7-5.8.0-src
  pypy2.7-5.8.0
  pypy2.7-5.9.0-src
  pypy2.7-5.9.0
  pypy2.7-5.10.0-src
  pypy2.7-5.10.0
  pypy2.7-6.0.0-src
  pypy2.7-6.0.0
  pypy2.7-7.0.0-src
  pypy2.7-7.0.0
  pypy2.7-7.1.0-src
  pypy2.7-7.1.0
  pypy2.7-7.1.1-src
  pypy2.7-7.1.1
  pypy3-dev
  pypy3-2.3.1-src
  pypy3-2.3.1
  pypy3-2.4.0-src
  pypy3-2.4.0
  pypy3.3-5.2-alpha1-src
  pypy3.3-5.2-alpha1
  pypy3.3-5.5-alpha-src
  pypy3.3-5.5-alpha
  pypy3.5-c-jit-latest
  pypy3.5-5.7-beta-src
  pypy3.5-5.7-beta
  pypy3.5-5.7.1-beta-src
  pypy3.5-5.7.1-beta
  pypy3.5-5.8.0-src
  pypy3.5-5.8.0
  pypy3.5-5.9.0-src
  pypy3.5-5.9.0
  pypy3.5-5.10.0-src
  pypy3.5-5.10.0
  pypy3.5-5.10.1-src
  pypy3.5-5.10.1
  pypy3.5-6.0.0-src
  pypy3.5-6.0.0
  pypy3.5-7.0.0-src
  pypy3.5-7.0.0
  pypy3.6-7.0.0-src
  pypy3.6-7.0.0
  pypy3.6-7.1.0-src
  pypy3.6-7.1.0
  pypy3.6-7.1.1-src
  pypy3.6-7.1.1
  pyston-0.5.1
  pyston-0.6.0
  pyston-0.6.1
  stackless-dev
  stackless-2.7-dev
  stackless-2.7.2
  stackless-2.7.3
  stackless-2.7.4
  stackless-2.7.5
  stackless-2.7.6
  stackless-2.7.7
  stackless-2.7.8
  stackless-2.7.9
  stackless-2.7.10
  stackless-2.7.11
  stackless-2.7.12
  stackless-2.7.14
  stackless-3.2.2
  stackless-3.2.5
  stackless-3.3.5
  stackless-3.3.7
  stackless-3.4-dev
  stackless-3.4.1
  stackless-3.4.2
  stackless-3.4.7
  stackless-3.5.4