I'm not ignoring you - just had to give this one some thought. The outcome of all this thinking is that there are too many moving parts to make a simple prediction. For example:
1) Does the Soviet Union remain the Soviet Union or do the Allies shove some émigré Romanov back on the gilded chair? What then? A constitutional monarchy or back to the old ways? Either way, there is the temptation to put a bunch of upstart and troublesome countries back under proper control like it was in the good old days when the world was properly managed.
2) US involvement. No idea what the views on European politics were of presidents Harding and Coolidge and on the degree to which they would have wished to be involved in the first place. If the Americans decided they weren't that interested, then all those silly ideas about self-determination may go away (in which case see 1 above
) Alternatively they might go full-fat on self determination and ask the Ukrainians, Belarusians, Lithuanians etc for their opinion, in which case Poland's eastern borders would definitely move westwards. There are certainly some advantages to breaking up the Soviet Union - Russia still remains a powerful counterbalance to Germany while it becomes much less of a threat to British interests in the Middle East and India. However how much you would want to weaken Russia is debatable (ie before she becomes useless as a counterbalance to Germany). At the same time, if Lloyd George is still in power and the Americans withdraw, Poland's prospects in the West will begin to look a damn sight less rosy also. Again, no idea either what the views of the British prime ministers who succeeded Lloyd George were.
3) Having been ploughed over back and forth (again) and being on the losing end of the stick, it is unlikely that the Poles themselves would have been as assertive (or aggressive if you prefer) in laying claim to territories, by force of hand where necessary, as they were in reality.