Does the bolt stay in well enough to retain the speedo cable?
The next best location is a transmission rear cover bolt just ahead of the normal spot. You'll need to source a longer bolt and either some washers, or a spacer, to fill the counter-sunk hole in the cover.
This is actually a better location for the ground than that silly breather bolt.
I've also heard that helicoils work well in that location if you want to try repairing the threads.