Thanks Pete! I'm definitely trying to do the right things so appreciate the collective wisdom here. Obviously I avoided a metal scraper, but my cleaning attempts with a plastic scraper I found to be basically ineffective! Hopefully no damage done....A couple of points:
1. I'll be the first, but you really need to be holding down your piston liners, as if they move you are into a much bigger job ...
2. The cleaning of the top of the block; like the head the most important thing is that it is FLAT, which is why I get nervous when people clean it with sand paper, or scotch brite type things, as you may unintentionally make low spots. Mechanics use scrapers to scrape the surface clean, they do not sand for this reason. It is unlikely that scotch brite would do damage, but with a sanding process the softest metal gets removed not the top most ...