Just some things I wanted to share here.

Don-you might want to take a hard look at the ring compressor your using.It doesn't take much,but a slight nick on the edge would cause you a problem going in.

As your putting in the pistons the walls are oiled up.Your turning the engine over by hand to put in the next piston.I suggest you watch the oil pattern on the wall of the last piston you put in.If you see anything weird like a line in that oiled cylinder,you stop and take out it back out to check it out.Not fool proof,but it might help catch problems.