Hurst 3836 64-67 A-Body Shifter

Looking at post #2 photos. To clear the case cover hexbolt head with the reverse linkage, why not just reverse the rectangular plate at the tranny so the offset is away from the trans case? That should give you the clearance needed to clear the bolt head.
If you don't have a Phillips head that fits the alignment slots in the shifter frame, pull out some Allen wrenches - find one that fits and it will be shorter, too.
Hope this helps...............................