I set up a blow thru system on my old '73.  I used an '81 turbo motor and put my 4 screw round tops on it.  I then fabricated a "plenum" that bolted to the two carbs that had an inlet for the turbo and several treaded holes for various accessories.  I then just turned the snail on the turbo facing up and conected it to the new plenum with a rubber hose.  I did have to modify the carbs a little, but not much.  I blocked the float vents, pulled out the throttle shafts and put a small grove in each end on the lathe.  I then put an oring that had an OD just barely larger than the shafts. This completely sealed the throats of the carbs up. I ran the car maybe 5 or 6 times before I needed to use it for a daily driver so I pulled that engine and put the original one back in.  I didn't get to do much tuning in, but could tell that there was definately potential there.  However, I think if I were to go turbo again I would just seek out the right FI setup. (probly much easier)  It was definately fun proving a few friends wrong that said it couldn't be done though.  I sold the engine a few years ago, but held on to the plenum and modified carbs just to hang on the wall if nothing else! Well, good luck with it if you give it a shot.  Feel free to PM me if you have any questions. -Richard