Making use of all the typical hot rod procedures will make a small difference, but don't expect huge HP gains. High compression pistons, hotter camshaft, mild porting and polishing of the intake and exhaust ports on a non-jet valve head, bigger valves, properly rebuilt distributor, a header and a CORRECTLY SIZED free-flow exhaust system, coupled with your Weber 38 jetted properly might gain you 30-40 hp. It will be expensive in both time and money, but if that's your goal, the necessary mods to make any engine flow better and make more power are well known.