Those are Dodge/Garrett turbos, baby 50trim t3's. At most they'll give you 400whp on a motor WITH intercooling. Regardless, I bet it's still a handful. Does it spool practically at idle??
I'd suggest you get a HX40 or HX50 with a divided housing. Both are cheap, would fit well between the block and radiator (w/electric fans), will aim right for the tophat if you don't intercool it - and support 65-99lbs/min of air. Those 50trim's can barely do 30lbs/min each, and taht doesn't factor in the tiny turbines.
If you are worried about spool, my friend's LS1 Mustang (yes) hits 5psi around 3500 with a T78. And that's a much larger turbo than even a HX50. It can flow something like 1500cfm, vs twin HX35's at 550cfm each, or 1000 from a single HX50.