Originally Posted by HTupolev

Why not? If what you're after is the feel of the older bikes, the easiest way to nail that is to use an older bike as a base. Modern steel often uses wider tubing and ends up a lot stiffer.

In many cases it's not like you'd actually need much modification anyway. As long as you're not buying something really old, or that uses a bunch of French standards, adding brifters is unlikely to require much "modification" besides re-spacing the rear end.