Justice,
According to the engine serial number data from GM in the
1957 Truck Data document the first part of the code (original stamping) breaks down as:
F = Flint plant
12 = December
12 = 12th day of December
H = 1957 3100-3800 series truck engine
I think the "060" is probably a machine shop added stamp. Probably indicating the block has been over-bored ".060" in the cylinders. Was a common practice to mark rebuilt engines in this fashion, depending on the shop that did the work.
Dan
