I have an idea what I think it's worth but I'm curious what others think, and hopefully some FE experts see this...
I have a 427 FE side oiler that I recently took out of a 68 Shelby GT500KR (wrong engine for the car is the reason I removed it) It was a running/driving car with the side oiler.
I know it is a side oiler and I know it has tunnel port heads - C7OE 6090K - with a polished tunnel port dual quad medium riser intake w/ dual holleys.
According to the documents - and I use the term loosely because it is mostly all hand written notes and records that came with the car, but it all does seem legit and everything else about the car is accurate - it is a 427 FE side oiler NASCAR block and all Ford/NASCAR internals, forged crank, etc. It has domed pistons, said to be 12.5:1 and we were told it only ran on race fuel and seemed to have a big cam and did make tons of power. According to the "paperwork" it hasn't been bored but I haven't opened it up yet to measure the cylinders or check out any internals.
The original owner of the car/engine builder is said to have worked at Ford and got all the parts & NASCAR block directly from Ford.
There are no casting #s on the pass side of the block, only a "E1" and "266" on the driver side under where the
oil filter mount goes.
Ok, thanks for reading, let me know what you think