Engine wise.. Probably a GT28 although I have seen someone make just over 350bhp with a good K04 hybrid, Rods (I.E makes decent ones), possibly uprate the exhaust valves. Someone like Nick at R-Tech/Bill at Badger5 could give you more of an idea of the injectors you'd need. The engines are pretty strong, its the rods that are supposedly the weakest part.
Then work on flow, good intercooler core, 2.5" IC pipework, 3" exhaust, probably a relentless manifold or similar, WMI, good TIP.
Just dont forget, it's all good and well having 350bhp, but if it was me I'd certainly want bigger brakes, and probably upgrade the suspension set up too. Im sure alot of people would also advise an LSD at that power.