Once you get the head off and see how much ridge there is and how scratched up the cyl walls are that's when you will know better how far to go. Just me but I would do the rings and rod bearings also and check the ring grooves for side clearance before ordering parts.
At that point a new set of pistons may well be necessary and a good idea anyway.
At that point a new set of pistons may well be necessary and a good idea anyway.