Thanks...I will be careful to not round any measurements based on assuming fractional units.
After posting my question, I browsed on to look at spur gear/rack drawings...so I can at least see what measurements matter...& That once upon a time there were 14-1/2 and 20 degree spur gears.
I suspect I'll find a metric vs. fractional conflict in availability/affordability or be stuck choosing between an overpriced parts-cam or cost-more-than-makes sense to repurpose the front standard high-quality option from someone like Boston Gear.
I am almost done fixing some loose dovetail joints...the front standard does have some nice capabilities like large geared rise/fall range, a smooth circular path clamping tilt mechanism, large L-R shift...not having the rest of the camera, it might make sense to rig up some frictional focus slide/clamp and forego the rack/pinion method.