I would leave it alone, get a better stock, and try some 52 gr bullets with 4895, I have yet to see a 22/250 that would not shot copetitive in a match with that load. In fact I have gotten new 22/250 that I have never fired, placed a scope on them , and won the match. I have yet to see any 22 barrel that shot well with 55 gr bullets no matter what the make. As far as shooting out to 300 yards, no problem. If you was to still rebarrel it, you may want to get a 1 in 9 or 8 twist 22/250, it will shot 80 gr bullet out past 1000 yards like a lazar beam. Out of what your have listed I would not pick any of them. If you only shooting paper why not a 6BR? The round is super accurate, hold many records at 600 and 1000 yards, low on recoil, it is also a real contender at 100 to 300 yards, and is one heck of a varminter cartridge.