Keep the main thing, the main thing, the whole goal in bedding the rail is to keep it as flat as possible when fully torqued, whether an issue exists in the receiver or the rail being less than true doesn't really matter. Use a surface ground straight edge to check the rail before putting it on the receiver and you'll quickly know whether it's straight or not and if your straight edge is wide enough, lay the rail on it and make sure there are no twists in it's static state with no pressure applied. Usually on a Remington receiver the barrel end will be more true (or flat) than the tang end. Simply position the rail where it will go on the barrel end and apply finger pressure to see if it moves on any plane and repeat on the tang end, this simple check will generally tell you where the focus needs to be. Of course for those whom enjoy a major case of OCD one can go to extreme effort and expense to assure that the entire assembly is absolutely straight, square and true on every axis, those guys probably don't read this stuff anyway.
