The benefits of upgrading to modern components will more than compensate for the additional weight they add. I upgraded my 89 Bianchi Cd'I to modern 105/ultegra and it's heavier than with the old components but the increased efficiency has made me a lot faster and that's the goal right? The primary goal of a speed oriented bike isn't to make it easy to carry upstairs to your appartment, it's to get the most output out of the least input.