Your stock 4bbl should be rated at 750CFM. A 650 Edel is going to be even less than you have now. Sounds like your tuning guys just don't like, or want to deal with, a quadrajet. Most mechanics don't have a clue how to make one work well. Sounds like they are trying to talk you into buying something they can just bolt on in a few minutes and send you on your way. It's just plan lazy. You gotta ask yourself what else are they going to let slide because they don't know or want to do the job right?