find a pedal spindle that uses cartridge bearings and bore the hole in the Jig large enough to press in the bearings, there won’t be any play, but you could screw down the jig onto your crank arm from the top. I’d weld a rod across the top of the pedal spindle in the jig to form a t-handle.
That’s an excellent idea. In effect it will be like a really funky pedal. Now I just have to think about how to incorporate your idea, but have changeable spindles for the right and left sides.
I really think this will work. I’m pretty excited about getting some dual hole cranks for my square taper Coker hub.