Rochester 2GC jet size

[Zeke...PA]

I'm running a Mercury manifold with a NOS Rochester 2GC, 7023064 small bore, I finally looked up the carb number and found it is off a Pontiac 389, whoa my engine was bumped to 3 5/16 bore but a long way from 389. I am running a crab distributor. I can down size the main jets, to #53, but don't know if the cluster is sized for the larger C.I., looks as if that's the only other replaceable jet, NLA, other than the power valve which I'm told is not sized?. I have found a 7008004 carb that's off a 265-283 Chevy . Am I better off building this carb than trying to resize the 389. Needless to say it was running a little rich. I am also running a PCV. Don't have an AF meter at this time. Thanks Zeke