I would assume anything that doesn't change the game's code is okay. If those custom weapon models require custom game code, then no.

base1-base3, imo, is probably the only IL friendly maps since you don't really pickup weapons (until base3 although what I'm saying is not well defining), but we should also try to explore this topic with other maps too.

For starters, the first 3 maps of the campaign should just be the easiest pick to throw in. Later levels, it might be difficult with Blaster start since, well, some levels require you to kill an enemy to progress, like security. Unless the plan is to give a pre-existing save with a pre-determined kit of weapons and powerups, then it would be simple for those select maps that come popping up. Otherwise, shooting a Tank with a blaster would just take forever -- in Easy, Hard and Nightmare skills.

This is just my thoughts on this, but I'm with the said topic.

As far as I'm aware, they only accept Vanilla. But stand clear from the steam port if you plan to do runs on a modern system. Go for the JoeQuake port.