3.23 to 3.55 isn't a big jump, just something i was throwing out there if you wanted some more acceleration and to help out with that cam - maybe go to 3.73 (?) if you wanted to step up acceleration even more. the a/c compressor will create more drag - maybe that's why you were advised to stray from the 484. the 484 seems like a pretty radical cam for a 383...kind of like throwing a 509 in a mild, factory spec 440...not going to perform that well, unless you rebuild and bump up the compression a bit.

PS. '71-2 Plymouth = best looking