OK so say I wanted to do an engine swap in the future (spare me the lecture of how it'* not cost effective and I should save my money, I've read your comments on other people posts and I get your point.) I don't have the facillities or experience to fab motor mounts to fit ,oh, say a LS4 in place of my 3.8.
Now, it'* possible by the time I get around to this project (hopefully in about 2 years) my father in law, who has done a few engine swaps, will have the place and tools I need to install the mounts and perform the swap.
Does anyone know of how I could go about getting the mounts I would need?

There is no book out there to give measurements, and to the best of my knowledge, no one that has ever done that before. I would first pull out your motor, put the other one in there so it fits with your tranny bolted up, install tranny mounts. I would then test fit the half shafts, and get your measurements correct, then take the LS4 stock mounts, L36 stock mounts a welder and a twelve pack and make something happen. It could be done, and would be insane

I would also go buy another car before I start, that would not be a weekend project.

I believe that FSMs give dimentions of frame pieces and motor mounts and all that other jaz that most people would hope to never use.

yes they do

Thank you guys, this project is at least a couple of years off. But I just want to do a little research to see what I'd be getting my self into.

Jack..one consideration would be to get the sub frame, The measurements for subframe mounts can be very surprisingly close.

90 bville were the same as 97 bville. Never know..everything might work right out. As if the engineers were told from these points stay within this space. The rest is for the bodyguys.