Good point Panic,
I am just going by the number on the body of the pump. The '56 and later models seem to all be marked -56, or after '61 -62. I just assumed that no one would put smaller diameter gears in a pump, and since it all seems to fit except the missing scavenger drive gear, it seems that it would be a '52 series.
The pump that came with the motor, had gears like the later Sportster sets, with 16 teeth and are larger, and flatter. Just like Sportster pump gears, but with the pin drive. It also had a pressure release valve, and my cases have the corresponding pressure release hole that feeds back to the cam area, just behind the sump drain. This pump did work at one time, but was matched with a bad pinion gear that slipped off the splines and miss timed the pump. It has no numbers stamped on it, but I have matched it with pictures of pumps off KR's.
We swapped it out for a '72 series, and have never been able to get the rings to seat for any good length of time in the last 20 years. Hence the move to a '52 numbered pump. Hoping to reduce consumption, and get more life out of it. Yes, also making torque plates, and using stock ring grove pistons. Likely Total Seal rings. Breather timing will likely be stock, unless we lengthen the duration by taking more metal from the pump tower closing side.
I am also going to plug up the side piston skirt oilers. It seems to be getting plenty of oil.
The gear I am looking for is definitely a scavenger gear, with pin drive and 14 teeth. Others I have found have been similar, close but no cigar!
I am happy as always to take any advice y'all are willing to give!