I really am glad that I have run my low compression 4.7 on midgrade or premium fuel for all these years now. The 2000 model year 4.7 don't have knock sensors and will ping when hot on low octane fuel. You may be able to find used pistons and rods from someone who has tweaked ther engine, because the hypereutectic pistons with the high mounted compression rings are relatively fragile. So they swap them out for forged rods an pistons.