it is sort of about how much money you have and want to spend on this. Your car obviously already has a SOHC in it, so you'll just have to turbo the engine that's already there, in which case you can either spend the money on a kit or create a custom kit. Either way lets say you boost at like 7psi and already at ~170hp
For a DOHC, you'll have to spend the money buying the swap, which is probably going to cost more than the turbo for the SOHC in itself, and then you'll have to turbo the new engine. But you'll be making more power at 7psi than the SOHC. Also the internals on a DOHC are stronger and can take more abuse than the internals on a SOHC. There are a lot of variables so you gotta narrow it down and see what u wanna get out of the engine and what your cash status is.