Its hard to explain but the single Su should be able to breathe enough air. The tuning of the carb will be a bit difficult as the jet will need to be drilled and you will need to profile the needle down pretty aggressively. I would start with the needle. Another way to do it would run a single dual barrel carb like a phh mikuni or webe, just run a 40mm but it will still be a bit big and hard to tune.
With draw through things are a bit different than in a na or blow through system and actually less carb is needed comparatively.
What you really need to concentrate on is have as little upward moving air after the carb and match port everything to keep from pooling. If everything can run downhill, that would be ideal as fuel air mixture is heavier and likes to go down.
You will need a turbo with the correct seal so as not to pull oil out of the center housing when the throttle is closed.
As for timing the least expensive to retard timing under boost is look for a MSD BTM. I have heard of messing with the plate in the distributor but I have not personally done this. Currently I am running 8deg advance at idle and no vac advance. I just havent installed my BTM. It idles great, has a little bog right off idle, great under acceleration, then gets a little pingy at wot and full boost. My engine is over 11:1 so its gonna be different for you. Current boost is at max 5psi.
Hint L28et or vg30et turbos have the correct seal for draw through.