You really don't have to give up that vintage look to get a modern bike. My Simoncini although now about 15 years old has the rear dropouts spaced for a 10 speed cassett and the steel is top quality, infact the weight of the frame/fork is only about 1lb more than CF equivalent, it is classic geometry and lines, the fork ends and chain stays are chrome (not really - actually the whole frame is nickle plated so where there is no paint it looks/shines like chrome). It is a real classic look. Just rebuilt it last fall with a Campy compact carbon group and put some nice wheels on it and I keep up with other riders on their newer CF or Ti rigs. In fact I feel I perform just as well on it as I do on my CF Specialized Tarmac.
So if you like a vintage look - you don't have to sacrifice performance for it.