Measure the average airspace difference with seal gone from cover, or seal hole bore minus the crank OD there. Buy 3 same size drill bits specifically picked to be like .002"-.006" say smaller in size than that airspace distance. Keep the number low so the feelers used can flex to match the curve of any shaft or bore there. Stick them in the space there in a triangular pattern while mounting the cover and then use feeler gauges unbolted from the holder (I use Autozone #25025 feeler gauge sets IIRC) to be separate to shim up to the exact size there. Or, drill bit plus .005" shim on each corner of the triangle and keep adding in threes (.006, .007., etc.) until tight and no slack there. When done tighten cover in place being sure any lap over to pan surface is even as well, use a straight edge and more feelers for checking there. Both sides need even for good squeeze at pan. Install seal carefully after all that. Yeah, harder but the cover is dead centered on crank now.
Done correctly you can imitate any OEM tool that centers bores up on shafts, I used the same on C3 trans oil pump (notorious for breakage if that not done) as well, it will center within .002" and run forever.
I got a whole can full of feeler gauge pieces, they get used on all kinds of stuff, you need them coming out your ears when doing modern day ATX setups........ ..............