I've seen those adaptors on open cowled Hot Rods and they look pretty cool with a bunch of flashy old stuff around them, but as said before the single four barrel is the best way to go for milage, reliability and performance. In the long run it's your call.
God Bless.
Tim http://yblockguy.com/
350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor
tim@yblockguy.com Visalia, California Just west of the Sequoias