^^^ Yup, if someone has the right butt for that saddle, it's a cool car.
A '65 block wouldn't have a VIN, so if need be, I suppose if there was a good '65 383 block out there, you'd have a back-up.
The reason I questioned whether the Seller meant .060 was, as others have mentioned, I'd expect a sonic test before going that far.
Last guy I used for block machining & recip balancing was Lee Sixt, who will sound familiar to older TF fans.
He sonic-checked before going less than that on a late '70s 440; two I had from that era had fairly significant core shift, and a few holes got sleeved on one of them.

Had a 470 cu with 11.6:1, solid roller and -1 heads, engine block was a -71 383 block with 4.375 bore. Raced that engine for a couple of season with out any issues.

So it's bored to 4.34 which 4.342" is a standard 400 B piston. so is it probably/presumably .092 over?

If it's an aftermarket KB piston it is probably near zero deck so it might be a snappy performer. If it's a stock low compression piston, probably not so much.

It's an odd-ball size (for that compression height) for anything other than a 400B, isn't it?

Have you talked to him? maybe he hit the 9 instead of 6 typing it in