Thanks to
@retr01 , I just prepared my starter dev HDA.
I think I won't bother with a HFV volume since basilisk II can easily deal with it. So can mini-vMac. scratch that - it doesn't open at all in mini-vMac, it asks to initialize it (sys 6.0.8 and 7.5.3) so I'll have to make a HFV as well.
Here are the files I put in - I also took the liberty to create a minimalistic barebones project that you can just duplicated in your scratch disk - just rename the files in your project (and refresh the added files in the project inside THINK C) and you'll have a jumpstart on having:
-1 main source file
-1 main resource file tied to your project that links with it when you build it; edit with ResEdit
-MacTraps linked by default so that the compiler know what you mean when you use standard Mac toolbox function names, globals, etc.
The view inside the opened project looks like: