How much gap are you running between the top of the gear and the shaft collar? It looks excessive to me. I've found on my stuff that if there's an excessive amount of up and down free play, the drive gear can change position too much in relation to the cam gear and it contributes significantly to gear wear, especially on bronze gears.

1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)