If the truck is all original, complete, and appearance will not require much to get it looking good I would leave this survivor original. Those kinds of trucks are getting harder to find.
If you want more modern performance and classic look I think it would be easier to get a 1960 - 69 truck. You will still have drum brakes though it should have a split master cylinder and self adjusting brakes. Then engine and drive train will do highway speeds all day.
Less modification needed. Easier to drop in bigger engines and match up to better transmissions.
