Thanks for the help on that carb. Only question then is which do you think would work best with the pump setup?
Have been trying to get outside to test the other carb mods but weather and other plans have not cooperated so far.
As for the 45 with end play, there are several reasons I see for it: Incorrect bearing width and/or assembly, as well as bearing wear. The design has the step on the crank come out flush with the front face of the front bearing so when the collar is slid onto the crank the proper preload is set by tightening everything down. In some cases there is a washer behind the drive washer, but I usually see these with key lock drives.
Along with pulling the prop driver and checking to see if the tapered collar is fully seated, (heat the drive washer, repeatedly if necessary) you should remove that collar as well to ensure there is nothing physical such as a nick or mark on the crank preventing it fully seating, You want to avoid using tools or anything that can mark the collar as that can then prevent the drive washer from seating true.
The statements about avoiding end play are correct, but IMO, the worst wear usually occurs when the engine is started with an electric driver that forces the rotating bits rearward to get adequate friction to spin.