I'm in the process of installing a billit 13-16 veri ratio box (third on the list).
I had a 1aauto(e-bay) 12:1 constant ratio box and it wasn't right for a big car and was very poorly rebuilt. It was nice around bends but on the straight away at 70-120 mph the car had an unstable feel to it I was twitchy.
It didn't have that nice steady big Pontiac feel.
As far as wheels go I would leave the factory wheel in if its in good shape. A smaller wheel isn't going to do much and with the higher effort of the harder valved box it would hurt performance and feel.
If you want to change wheels try the Grant wood wheel its a little thick for my taste but the price is right.
I used a chineese repo 65-66 wood Pontiac wheel. Its flaking and I can't get it back off!
I'm sorry I didn't look harder. There are a lot of good American made aftermarket wheels out there.
I love that 57 Olds you have!
Check out the Performance Years web site under 62-66 Big car.