this car was based on the c4 chassis corvette, it was really a 'glass bodied kit car that was put out in limited numbers, and I think a few were actual race cars. but if you want to replicate a street version, just check out any C-4 corvette, and you'll have most of the reference material you need.
I'm sure they did some sort of forced induction, or fuel/air system modification on the real cars. I think the AMT kit is just a re-bodied c-4, which would be really close to the real car anyway.
I here's a site with a little info, but only one pic.
just search google, gsa grand sport 90