Best replacement pistons for stock '69 engine

Mattax said

Yes. Take Measurements First.
JBurch used 68 cc, but he's just estimating. One book says '69 could cc as low as 60. That's the minimum spec and you'll never find that on an untouched original. Chamber volume measurement isn't that difficult. Well worth it IMO.

Since the machinist had to go .040 over on the bore and you say the pistons have 4 valve recesses, it is likely this engine has been rebuilt once before. I would not assume anything. Its possible the heads are not even from a '69 318, although the book show the same casting through '74.

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Interesting. The machinist seemed to think that it had not been rebuilt before due to the type of cylinder head gasket and the nylon timing gear (which was the engine's eventual undoing). It was very worn out and only a couple cylinders even broke 100psi, plus it had more sludge than I had ever seen. But, it's certainly possible it was rebuilt early on.

It seems like the KB pistons will probably be my only option to get close (or slightly higher) than stock CR, but to be sure I've ordered a burette so I can accurately cc the heads.

I'll take a look at my '69 pistons and see if they're in decent shape - I know at least one missed the towel I had set up and chipped itself hitting the concrete on the way out. To be honest I wasn't as careful with them as I could have been, since I assumed there was no use for worn, stock 318 pistons.