I learned a lot about the T5 when I went looking for one to put into my '95 Astro, but you're right, it's the tailhousings and parts contained within them which differ the most between the various T5s. I have some long term S-10 parts plans, so this isn't totally off topic. I think a long bed and frame to match would be a good thing to have available.
Funny... I had an 87 Astro with an Iron Duke and a T5 years ago... Could have walked faster backward but it was kind of neat! Keep me in mind if/when you decide to cast some of them, I'd be interested in several no matter the configuration.
To the wheel discussion... Seems like all the kit makers reuse the same tires over and over whether appropriate or not (tires must either be hard to do, or expensive to license, or something?) it seems bizarre to me that they would tool up the 4wd wheels for the S10 , but later do the AWD parts (which are mostly indistinguishable from 4wd parts) for the Syclone. Can't help but wonder if there were some missing memo's on the S10 project back then. We might easily have been having a thread about suitable donor kits for 2wd front suspension instead!