i've herd a lot of negative things about blow through systems. plus i don't think you can have a stock holley, edelbrock, or any carb at that being used in a blow through system. if it were so easy and drivable you would see a lot of people doing it.
i use to have a four barrle conversion on my l26 and it did about 15 miles per gallon average. i don't even want to think how bad it would be if i had a turbo in addition to that humungus 4 barrel carburetor.
if any one is thinking about doing anything with a turbo you should first read my favorite book: maximum boost.
just my two cents