You don't need the ECS Denise for 50/60Hz switching, just the updated Agnus. I had a few PAL reset tools for running games on my 1.3 A500 with a 512k trapdoor card. (The best one was the "BANZAI" tool.) IIRC, my Rev 6 motherboard needed a modification for 1MB chip (instead of 512k chip / 512k "slow") to get it working. I bought a new 1MB Agnus just to open it up and discover it already had it from the factory.