I understand what you want to do but as John says, basically, you're mixing old and new.
Today's modern windows don't work with 'old' systems. When windows are 'replaced', they're done so from the rough opening. Meaning, the entire old window is removed and the new one is, first, framed out (roughed in), then installed (or finished). If you want old-style looking windows, you can get them in a 'modern' form. Check around with local door and window stores and see what they have. You may have to search the WEB, once you know what you're looking for, for a specialty window.
As an aside, I have this philosophy. Once, I replace a few 'bad parts' in a toilet bowel. But when I went to test the toilet, something else went wrong. And when I fixed THAT problem, yet something else went wrong. To make a long story short, I ended up replacing the ENTIRE guts and such of the toilet before it ended up working right! I spent 3x's as much time on the job as I should when I should have just gone out and bought all the new parts and done the ENTIER replacement from the get-go. So the moral of the story is: Old parts don't necessarily always work with NEW ones.