LMFAO 200hp turbos would be on boost at like 1000rpm on a 5.7L V8. I think you'll be wanting something more in the 400-600hp range EACH. GT2540R (smallest Id go 440hp), GT30R something like that.
Go for an auto gearbox I recon. You'll have enough troubles finding traction without trying to change gears as well. I'm sure theres plenty of places out there with big auto boxes for Gen IIIs