Wish I could picture in my mind what the tab is supposed to stop against. It should be obvious with the cover in hand. I would take some straight edge measurements with the new governor in place to be sure the depth of the tab is correct. The use or not use of the spacer is important. Best I remember, the ball cage should fit flush to the front of the cam gear, not stressed or bent as the nut is tightened. It should have instructions what to look for.
The governor cover tab is supposed to be positioned at 8:00 when the timing cover is installed, so it will not be crushed and will turn around to the proper stop when started.
Here's a how to if you don't have the shop manual.
Pay particular attention to the nut torque in the video!