According to my SOHC book, "Ford 427 Single Overhead Cam Engine Service Manual", the distributor part number is C5AF-12127-BY, which is what you've got. I don't know what the stock Ford distributor was, or if it was any different. My book says the following about the distributor:
"The distributor uses a dual breaker system consisting of two pair of low-mass tungsten contacts. The reduction in mass permits higher rpm's with lower contact tension, thus reducing breaker cam wear. The distributor cam is precision ground and hand buffed to further minimize the high speed rubbing block wear. The cam and shaft assemblies are selectively fitted so that a running distributor properly supported at the driven end - as in an engine installation - will have a firing point spread from cylinder to cylinder within 1/2 degree of camshaft timing."
No idea on the value, but most original SOHC stuff is expensive. I always use aftermarket distributors in my engines, due to their electronic triggering and their easy availability.
