I saw one lathe that was about 16" swing, that had the bed cut away down to the level of the leadscrew for nearly 12" in length, that was quite extreme to say the least, I think good blow could have broken it in half; I have seen a good many other lathes that the ways or portions of them cut away for some special job, it is not uncommon. I think that if it is done, it should be done neatly; having said that, I would never do so. If you need a larger swing, block the headstock up, even just temporarily. Where I apprenticed, they had a 40" lathe blocked up to swing 87"; at one point it was blocked up even higher, but this was later removed, as it was too unstable, even with braces to the wall and floor.