4x4mm steel u-joint

[simplechamp]

I would say with a vice, hammer, pin punch, etc. it might be possible

Did you ever consider using center dogbones and drivecups instead of a universal joint? You should be able to easily find the right length dogbone, and for the center drives it should be fine as long as the angles aren't too steep on your new relocated CD location. Gotta have CVD/universal in the front, and probably should in the rear, but in the center a dogbone is fine IMO.