Hi Peter, If it were mine I would probably leave it alone. I don't see that it would matter however if you were to thoroughly photo document its original state and substitute your preferred components. I would also place all the original parts in a box and keep them. The inevitable new keeper of the bike will no doubt thank you. I am curious how much of the existing equipment is actually Campagnolo? In the early 50's they didn't make anything like a complete groupo. I would have thought that only the hubs , derailleurs and shift levers would be Campy. That would seem to leave brakes and crank-set up to the original buyer. It also probably has a British headset and bottom bracket, did Campagnolo even make British thread parts this early? The C.L. crank-set sounds great along with the Harden hubs, but the 1950's British derailleurs seem to be somewhat lacking compared to early G.S. Whatever you do it sounds like a great bike.
Greg Lone
Langley B.C.
Canada