My last 360 had KB hypers and 10.5:1 true static compression. I put 25k miles on that thing over 6 years with lots of detonation; cam was mismatched for the compression and cubes and built way too much cylinder pressure at low RPMs. Didn't matter if I used the best premium gas I could find. I mean I pinged that thing almost every time I took it out and it held together for that long. Finally when it did let go it butted the top ring, busted a chunk off the top of one of the pistons and proceeded to trash the piston pin and put a huge crack in the cylinder wall.
I'd be surprised if you really broke a ring land because based on what happened to my engine I would think yours would have some serious internal damage from a chunk of aluminum getting repeatedly smashed up inside the cylinder up against the head... just my $0.02
Oh and now my current 360/5.9 is only 9:1 compression with aluminum heads and runs on regular gas with no pinging whatsoever lol. Learned my lesson with high compression on the street, it's a fine line to walk and oftentimes not worth it.