You are correct with the icing of the carb,, that is when the carb is to far away from the turbo, and the vacume problem is not a real problem but I would sugest a vacume release valve just after the carb, SU's got them build on the butterfly,, simple engineering will sort on intake manifold to the turbo for other carbs
Suck through is simple and make horses,, Blow through make more horses if you get it sorted,, suck through is much simpler to setup with a minumum budget,, you can spend the exstra bucks on brakes
All the best with the project,, anyway you do it,, turbo's rock