[Davescamaro]

350whp on a good tune with a forged block? I would assume more. The turbo if not mistaken oem is a mitsubishi td04 (same as evoX) and they boost roughly 20-28psi from hp tuners.
I would think stock turbo and injectors he could achieve 400+ knowing that his valve train is now beefed up. I've seen cobalts with smaller turbos and 60lb injectors reach over 500whp.
Not saying your wrong at all, safe wise 350ish would be ideal without upgrading turbo size and injectors.
To add, I dont know of any aftermarket torque converters. I'm more of a manual transmission type of driver and that would require a heavier duty clutch for maintaining power transfer from output shaft to input shaft. A lighter flywheel would help with quicker revs and launch control.