Shimming the distributor is probably the quickest fix unless you're willing to drop the oil pan and make a more permanent change like swapping the intermediate shaft, etc. If you do decide to go with the shims, make the fix semi-permanent by gluing the shim(s) to the distributor housing. There should be a little clearance up and down to the distributor shaft with everything buttoned down to prevent drag and wear to the distributor.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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