1973 Dodge SB Distributor will not seat against block

I have a 1973 Dodge with original 360 V-8 engine. The car starts and drives okay. However the base of the distributor does not seat against the top of the block. There is about 1/8 inch of clearance between the top of the block & bottom of the distributor base. Further the distributor is very hard to turn when I set timing.

Thus far I have tried removing the distributor and tapping down on the oil pump driveshaft to see if it is not fully seated on the bushing. I also cleaned out the slot...

1973 Dodge SB Distributor will not seat against block
Author: 1970FuryConv