Ron,
Well that's good news, then! IF the casting number tells you it's the '54 mold, and the date code and the head casting number tell you '59, and there's no captain bars or serial number ... then yes, I think you have found the younger brother to mine
and you will have a very easy swap. Now, the mistake I made was to order the older style main bearings. Because the block was built in 1959, they were already using the newer style bearings, so you will want to check to see which style main bearings it has before you order new ones. My guess is that it will have the newer style.
As a side note -- Over the weekend, I managed to catch up with the gang in Winchester, VA. This was my 261's first major road trip since the rebuild -- about 300 miles total, most of it at sustained highway speeds* ( did 70 MPH at one point, according to my GPS, probably on I-66). The engine ran flawlessly and did not use any oil (minimal drips). Once again, BIG thanks to Hotrod Lincoln in coaching us through a rebuild done *right.*
And seeing as how we honed the cylinders, we think this engine is a 262 now
* Have I mentioned my new Huck brakes and new set of 17-inch bias ply tires?
