@AtaraxicShrug, If you are after simulations of a negatives based on real film stocks, you can get a decently realistic virtual scan of a negative with agx-emulsion.
Here is a quick example example (virtual negative and virtual RA-4 print):
There is an options to be clicked for computing negatives (
compute negative tick box).
I am not sure this is the tool that could let you experiment easily with other virtual printing processes. I am interested in them if you get any good ideas/results, though. 