Hey Toyz,
I have dual quads on my project engine. Most people will tell you that they are just for looks, that a single 4 barrel will work as well or better. I had always thought when I was just starting out with cars that by now I'd be running a blower, but I kind of got sidetracked for 20 years paying for a house. I still would like to build one (not buy) as they take a lot of preparation before you ever bolt them on. Blowers are a 'make or break' thing, if you don't have the bottom built strong enough, something's gonna break.
Oh, BTW, even with a blower, you still need something on top of it - like 2 fours! You can have your cake and eat it too!! The incredible John Z. can give you the straight dope on the duals, probably blowers too, even though GM never offered them on cars. Live your dream!!!
Craig