My 30 year old custom built Davidson is still going strong. I'm still using the original Campy NR shifters and rear derailleur, although I had to replace the matching front 2 years ago as the mount had cracked. With that campy NR setup I'm using a 10 speed Shimano wheel and it shifts flawlessly. I recently replaced the original Modolo Speedy brakes and levers with inexpensive Tektro ones, and the Tektro are MUCH better. The crank is a Chorus 10sp, except the bottom bracket is the original Zeus square taper. When I tried to use the Chorus BB, I couldn't get the old fixed cup off. I repacked the old BB and felt how smooth it still is and left it. Saddle is a new Performance store brand racing saddle, the seat post is carbon fiber. Wheels are Velomax from before the buyout by Easton. Bars and stem are original. Bottom line is that most of the important parts are new, but some are old. I'd have to say the modern parts are mostly better.