I make this in sort of a non traditional way, no hob involved. Results have been good. Since the gears are cut top down on a mill, they aren't perfectly round (or as round as a hobbed gear anyways), but being aluminum (running against steel) they self clearance after a short amount of break-in. Wear tends to be very minimal after break-in. New gears are not being produced for these engines, the new old stock gears are made of nylon and literally are falling apart since they are all 50 years old.
Lately, it's not uncommon for me to have several days of uptime with UCCNC. I went from Tuesday to Sunday just this last week. With 40 hours of C time in there. I don't do this professionally, it's more of a hobby business, but this gear has been a really hot seller lately. I built it for our vintage sports racer since we were breaking gears often, and the gear just sort of started selling.
I'll add, the ProbeIt plugin has been critical for this work. The B side machining requires I probe the internal bore to establish reference, and I couldn't be happier with how consistently I can setup that back side. The probe calibration is key, IMO.
p.s. I tried to resize the images here on the forum with bbcode, I am guessing either bbcode doesn't do that anymore or that it's disabled on the forum, so I apologize for cutoff/oversize images.