I've got one set of .030. used forged SRP for. $150.

Exactly!

See if you engine guy can go to a 4.500 bore.

Most 502's can go to .100" over. Have it sonic checked but casting core shift in these modern blocks is extremely rare.

I have a brand-new set of SRP's in 4.500. They're boxed to go back- they shipped me too many sets on my order. If you want them, they're yours for $500 shipped.

P.S.

IIRC, the JE/SRP clearance for cold-water marine is about .006" Hard to imagine that the stock block won't clean up on one oversize... unless there was mechanical damage.

I guess it's 4.500 minus 4.466 = .0034

Is the stock bore 4.466 or 4.470? I've seen both numbers, am I to assume the 4.470 is just rounded up from 4.466, or is 4.470 the actual bore?

Stock bore on a 502 is 4.466". .so I believe this is where he is getting the .034" over. You just need to go to a 4.500" bore piston or a 4.530" bore piston. No special parts needed.

I hear the idea was you can get a quick freshen hone taking you from stock 4.466 to 4.4700, then you have rebuilds to 4.50, 4.53, 4.56, 4.60, etc.

I thought is was 4.468 on a standard 502, thus .032 brings us home to 509's - ?

I have some used Diamond 502 + 0.030" pistons if anyone is interested.