Then skip the eagle kit.

What is the bore of the block ? to get 512 I'm having to go out to a 4.380 bore. unless the block needs it I would only bore it out as far as it needs to go and no further.

Crunching numbers the 17cc dish piston is your best choice , it will give you about 10.3 ...



Bore is 4.375, was previously .040 and cleaned up nice at .050. When I calculate the CR with 17cc dish I'm getting 10.8 w/ 80cc heads. Are you using 84cc? I'm using this site:
https://www.uempistons.com/index.php?main_page=calculators&type=comp