After quite some time now, and a wrong size key purchase, I went to work yesterday to fit the new gibkey. First was the requirement to shorten the key by 3/8" as I did not want it sticking out too far from the pinion, when in position.
Here is the completed key:
I reduced the taper in the key thickness to less than 1/32" of an inch so that there would be good holding power and more of a spread of the torsional forces along the width of the pinion/shaft keying.
Before removing the old key I tied up the press with my 5 lbs sledge between platen and bed, and marked the gear engagement so that I would not loose mechanical timing when the key was out.
And here it is driven in quite solid, in all it's properly aligned glory:
I'm sure glad I went through this trouble, as the pinion would have come loose, likely at some inopportune time. As well, the gear teeth were just starting to mark up, with the pinion pushed too far over, and with the smaller meshing there was obviously higher load (and wear on the teeth) taking place.