340 engine repair/build questions

I had the exact same situation.

Bores cleaned up @ .040 but one needed 1 sleeve. I used the exact same new Silvolites that you currently have. They are a cast piston that installed at .017 above my deck. I redid my stock rods and used the original forged crank and did not balance. Engine runs strong and smooth. Like you, this is a punchy cruiser engine.

If it were me, I'd try cleaning the rust off with solvent and a scotch brite or some other mild abrasive. Any pits in the "stroke zone" and it would be off to the machine shop for me.

Good luck.
Obviously costs will vary by location but out of curiosity, what did that cost ya? I just assumed they’ll need to be balanced. I’m sure it would be better balanced but for what it’s used for, if it’s not required..