Don't do it.

I have a frame coming that I'm reasonably certain is 753. It's spaced at 126, and I'm going to run it as a fixed gear (not a Drew'd one). I had to limit my search for a suitable rear hub to one spaced at 126, since anything else would mean respacing. Of special concern on 753 frames is separation at the chainstay bridge - and this even without adding the stress of changing the spacing.