[Rick_Bee]

No need to change either pulley, that would create monumental problems as belts are not available in "any" size.

Find out where the oil is coming from don't shotgun replacement parts, it might be trans juice....

I would install a helicoil in the cover bolt to strengthen the threads and then machine back the cover for more belt clearance.
One of those little belt sanders or a die grinder with a burr would do the job nicely on the bike.
Mark it with a sharpie and take the belt off so you have room to work.

 

[Rick_Bee]

Multiple applications of the penetrating type loctite?

 

[Rick_Bee]

Cowpie is late
Ratchet top is early

A cowpie has the shifter cam flattened out and rotates on a vertical axis.

A ratchet top the shift cam is in a drum configuration and rotates horizontally.