I know the 400 has a bigger bore but if my calculations are correct I can use a low compression 440 piston in a .060 over size in a 400 with a smaller oversize and with the added compression height I could really bump the compression on an budget 400. Am I missing something?

I was also trying to come up with a way to use a LY rod in a 400 to get the compression up but I keep comeing up with the piston too far out the deck, is there an off the shelf piston for this scenario?

I already have 516 heads with big ex valves and some minor bowl work and milled .010 but compression ratio is still pretty low.