71 Dart / 5.9 Magnum / Procharger

Pulled the engine. When I got the heads off 7 out of 8 pistons were hurt. Turns out 27 degrees of timing and pump gas was causing detonation during drag week. Once I realized I started adding race gas and backing off the timing but it must have been too late. I think the engine was finally happy at around 22 degrees of timing with a 50/50 mixture of 110 and 93 pump gas but by then the damage was done.

Luckily it appears the pistons were all that was hurt. The rings were gapped at .022 top and .024 bottom. I'm thinking this was too tight and the rings butted together exploding the tops of the pistons. Everything else looks good so I've ordered new pistons and will gap the rings bigger. Any suggestions on the gap? This is 10 lbs of boost.