Howdy
I tried to find a pic of what that rig looks like, couldnt. But it sounds like it is a van chasis? If so, it will be difficult to mount a turbo with any type of "normal" setup. The best route is stated above, find/build a hummer or stock van turbo set up, a 6.5 will work just fine. They mounted the turbo in the rear center of the intake valley. These are not hard to find as many small buses and transit vehicles had that setup.
If you REALLY want to fab things up yourself and use other parts, there was a member a long time ago that did the remote mounted turbo behind the motor down under the floor boards. You will lose allot of exhaust input that spins up the turbo.
On the subject of intercooling....intercooling in general doesn't give you a big boost in power, but it does allow you to run a little higher boost with a cooler air charge. It is safer for your engine and all turbo engines like a cooler aircharge. The extra plumbing will decrease your boost level. It might be easier to use water injection, check that out.
Overall, IMHO, make sure you have a complete set of gauges and then start tuning your engine for boost, fuel and egt based on a loaded rig.
Good luck! Hope this helps!!!
1996 Chvy 3500 CCDWLB 6.5 Heathed, NO vac, marine injctrs, ARB bumper, BIG pipe, 3" lift, bright lights, bypass oil system.
1986 Chvy 6.2 M1009 blazer RAM AIR, Headers, Custom interior
2001 Chinook RV, V10 gas
1974 John Deere 1530 diesel tractor
1993 John Deere 455 Diesel lawn mower
1967 GTO, 1989 Honda Transalp
2009 VW Jetta TDI, flashed and piped, 6speed, fun car!
1998 6.5 suburban, stock, daughter's
1993 6.5 3500 CCSWLB GM8, Heathed, big exhaust, gauges, Son's
1984 6.2 ATS turbo 3500, SCDWLB - Son's
3 kids, 1 wife, 1 dog
Gunsmith, Tactics Instructor, Fabricator USMC 87-93 Semper Fi!