I don't have any experience with 10g batches, however 30 quarts is a pretty tight fit for a 5-gallon batch, so I would think 50 quarts would be REALLY tight for a batch twice the size...
However, I think you'd have quite a bit better luck if you tried foam control drops. I did a 5-gal batch which had like less than 2 inches of headspace pre-boil in the 30qt pot and it didn't even threaten to boil over, thanks to that stuff.