3769925. Captains bars above the starter, with two other numbers CON3 L174 above the starter too. I thought there was always a number stamped on the Distributor flat, but this one doesn't have any numbers there. The head is an 848 so not originally a 261 head. When I took my original 261 to my engine shop, they found cracks in the block and got me a new one, so I have zero information on its history.
I had them clean, magnaflux, bore to .040 over, do the normal prep, turn the crank, etc and then sell me the new pistons, cam, rings, etc, etc. and I did everything myself. So, really wish I had known! Now that its on the frame, tuned and adjusted, bad time to find it.