Unless you're looking to do an ifs swap, there are several front disk kits available that will convert the stock axle. Same goes for a power steering conversion. Most, if not all, of the parts suppliers (such as American Classic) listed on the Links page carry those kits.
As far as a rear axle, the stock Eaton HO36 is well up to the task. Gearing is 3.90 stock, with a 4.10 and 3.38 optional. The 3.38 gearset is still available if you want better gearing. That axle was very popular in the racing circles, many of the Gassers from the '60s used them (including the famous Stone Woods Cook Swindler) along with many circle track stock cars (Black Widow '57 Chevy).
