First things first..
Do you really want to run one turbo ? generally single turbo V engines use a large turbo, which can be a bit unresponsive, but provide a lot of power. Thus twin turbo conversions are much more popular as it allows the use of smaller more responsive turbos. This raises another question.. do you want sequential turbos ? this basically lets you have a small turbo that spins up very easily to begin producing boost and then a larger turbo to provide more power, the idea is that the small one gives the response and the larger one high boost. You can just run a pair of turbos in parallel ( i.e. both the same, one for each bank ). What pistons have you got ? if they are cast you'll need something stronger to take anything past 5/6psi. Carbs & Turbos don't always go together, suggest you think about swapping to a mappable ECU that can control the fuelling & ignition properly, rather than the "poke and hope" of a carb setup. Think about the rods as well, these may need to be strengthened ( i.e. replaced ) before any worthwhile boost is used.
IMHO unless its doing 12psi upwards you're wasting your time.