as far as i know 3.38 is the only other gear set available. This guy below is a fellow stovebolter too. I'd ask him if you have specific questions.

https://www.ebay.com/itm/276824024320

If you drive in the foothills or mountains, you might want to keep you 3.90 gears in there. I know my well used 235 prefers the original gears & I'm going back to them. Good luck.

1959 3100, original 235/3 on the tree w/overdrive. Carter YF 2100S carb, 205/75/15 w/front sway bar