Where did some of you run the ground for electronic speedo sending unit?

I have the stock speedo in mine but a good place for the ground would be behind one of the nuts on the steering column support bracket.

I was looking for somewhere closer to the sending unit itself.

You could even wire it to the same place where the radio ground is. It's just a wire that won't be seen behind the dash anyway.

where did you mount the sending unit Jim?

The bullet retainer has a 1/4" bolt, That should work.