We run the S366 T-4 0.91 73 with decent success. Its priced around $800. Make your own turbo inlet flange, free. The GT4202 works as well, depends on turbine AR and turbine inlet flange
I put a plug into the turbo compressor inlet side and pressurize the entire system. Its a sure way to see where boost leaks are. Just make sure pressures dont go over 30psi. Head gaskets are a mother to fix.:)