Help me identify this Ford engine for a customer...

It's an FE of "some sort". Unfortunately, the only way to tell which one it is is to remove the oil pan and see which crankshaft it has. There are no identifying numbers whatsoever on the outside. Anywhere. The 351M and 400 were the same way. No numbers at all to identify them. It's definitely an FE. The intake manifold makes up the upper valve cover rail on the cylinder heads. It'll have "352" cast on it somewhere.....and everybody thinks they have a 352 when they see that, but ALL of them have that. At least all of them I've ever had in my hands, seen or read about. The non adjustable rockers mean hydraulic lifters. If and until you tear it down, you won't know what it is. A lot of people try to measure the stroke with like a coat hanger wire through a spark plug hole, but it won't work because of the extreme angle of the plug hole to the cylinder. You could try it I guess and see what you come up with.