...This involved fixing bugs, reducing stack usage and making the code compile in 16bit via Pure C (Turbo C for the Atari ST).
Source credits include:
Martin Richards - BCPL Kit
http://www.cl.cam.ac.uk/~mr10/
Robert Nordier (Translated interp to C)
http://www.nordier.com/
Serge Vakulenko (Translated cg/syn/trn to C)
https://github.com/sergev/b
I'm sure there are other names, but those are the ones on the source files.
The code now compiles clean for the Atari ST, so it should work for anything else.