The issue: Right Stuff Detailing front disc brakes. Studs don't come to the edge of the Centerlines, let alone past the edge of the wheel to be legal at any track. I know there isn't enough engagement on the lugs.
The question : what is the rule of thumb for knurl size? The hole is 0.618. I know you want a larger knurl, but how much?
Would a 0.625 knurl be large enough or should it be larger to assure they won't spin in the rotor?
Thanks.

A threaded shank should give you enough thread engagement to be legal.
I ran into this with a disc conversion I did on a '66 Cyclone with auto drags on the front.
The meat of the rim was over an inch thick and the lugs had 3/4 " shanks.
I forget which press in studs I used , but scoured the Dorman cabinet at a local auto parts store and found the longest I could.
They came out of the rim by about 1/2 " , and 1/4 " was just a bull nose on the stud.
But there was over an inch of thread penetration , which is plenty.

Call Drdiff he should have what you need I got them from him for my junk

I used Right Stuff for my disc brake conversion and ran Centerline Auto Drags for a while.. I never had a problem passing tech. This was at Quaker City, Norwalk and 42.

i go for around a .010-.015 press fit on a knurled stud.
this has worked for me for over 50yrs.
when pressing studs, either in or out, support the axle or hub flange well to avoid bending the flange.

That's what I was looking for. Thank you.