joe,
Yes you can add the proform stuff and spen even more money, but seeing that that carb has all sorts of mix and match stuff on it, I would bet that there may be some mods on the inside that you have not seen yet,
sometimes its best to start with a fresher piece. Havin said that you can always take it apart and make sure that there are no stripped threads and welded or modified p/v passages and what not.
Just like the real carb experts on the board say its best to restore it back with the parts it takes and then tune from there than to try to tune a carb that has 850 baseplate, 750 metering block, 650 jets. etc etc,
Been there and did that after spending tons and getting it to run good, or so I believed I borrowed a fresh out o the box carb and dropped my ET, just my .02