I have never had any problems with interchangeability between any of the bolts in my Mosins. Unless I have seen major bolt head wear that would cause me to question the safety of the headspacing, I have never worried. Imperial, Soviet, Polish and Hungarian bolts and mix-and-matches all have been fine.
I pretty much just test them to make sure they function properlly before, sometimes I have had some sticks, so I simply don't use that bolt head.
Part of the beauty of that Mosin is the fact they made them like tanks and for peasant soldiers who didn't know the first thing about headspacing and the like, I wouldn't be too concerned.