1. Like a couple of idiots we re-installed a flex plate with a few teeth missing during the rebuild, because we were in the middle of nowhere and chose not to get a new one...................I'll have it replaced sometime in the future. The rebuild was 22 years ago and guess what? No problems, though on occasion It sticks a bit.
2. I had some issues two years ago, and at some point it sounded similar to yours. I replaced two starters, and added shims for it, so the starter was out at least three times before it was right. I also replaced the battery once.
Lessons learned:
A. Never go cheap on a battery. It should be high quality.
B. Be sure the starter is high quality.
C. It hasn't been a problem, but darn I wish I had replaced that flex plate.
Incidentally, you'll make life easier adding connectors for the two wires to the starter. I use these:
