You'd have to get a 40T chainring to get the same gearing as a 48x19, and the wheel would move so far back in the dropouts (track ends) that you'd probably have to remove chain links anyway. The only thing is that you may have to scrounge an extra chain link if you don't have an old chain lying around, and you won't know what size (1/8 or 3/32) you'll need until the bike arrives. You should get a chainwhip and lockring tool, and a chain tool.