You misunderstand. Just because you have a 4bbl manifold doesn't necessarily mean you need a 4bbl throttle body. EG the old Holley Pro-jection was a hi-flow 2BBL TBI that fit (with supplied adapter) on a 4BBL manifold
Post 7 is what I started with, 75 bucks, I think, off CL
http://www.forabodiesonly.com/mopar/showthread.php?t=262068
You can find those TBI 2bbl units all over on ebay and other places.
