i think you could hit 350 with a few mods to the turbo, maybe a compressor wheel and housing, or look at the max flow dodge elbow by pacbrake, i think that would help. i going to be something similar to my truck soon i hope, though i have no idea the power it will produce.
if you want the turbo to last at that power there are a lot of things, some small, that you can maybe should do that seem to make a difference. some on here may disagree with me but i have done them, i like the way they perform, and i think they work. however they may not work for you, i wont make that promise.
i want to mention that my truck used to smoke heavily, i have not touched the fuel settings but many of these mods have made a significant difference in reducing the smoke. now it just puts out a little bit on the low end when i hammer down hard.
my list of mods, f. a. s. s. , derale heat sink fuel cooler, vulcan draw straw, ddp stage 1 injectors, afe drop in air filter, afe torgue tube, tag I, heat products turbo blanket and exhaust heat wrap over the whole manifold, #10 plate full forward, light afc spring loosened all the way, hamilton big stick cam, timing at about 18*, full 4" straight pipe exhaust, 14cm2 non wastegated exhaust housing.
planned mods, heat shielding on intake tube and air box for more reflection of exhaust heat, 60mm turbo compressor and housing, 12cm2 wastegated housing, boost elbow, heavy spring wastegate, max flow elbow from pacbrake.
some of the mods you may not want to get into, the cam is a big project, but made a big difference too, the other ones are all pretty easy and all seem to contribute and add up in small ways. ive also brought my fuel mileage up from 14 15 highway to 16 17 highway