Replace service kit with an adjuster clutch ball at fork

[gzig5]

Should be very straight forward to do the external shape, but that partial D profile in the hole is going to be a trick.   How would you go about that?  I've got an idea but I don't think it is a good one. 

[YellowThumper]

Dont really know what inside looks like but I have access to EDM wire and conventional sinker EDM if necessary. Split piece to allow internal access and then weld together as assembly.
Whatever Avenue gets it made

[70 Challenger Lover]

Let me know if any of these photos are not good enough.

[70 Challenger Lover]

I think the measurements speak for themselves but on the last couple shots, the hole is 3/8" but the flat measures .327 side to side. The depth of the flat as measured from the backside is .172