I received my new shift knob and thought I'd take a minute to post some pics and add some additional information.
I have an '87 with G50 gearbox. When I received the shift knob, I also received a shim and allen head screwdriver for the 2 set screws in the base of the knob:
The knob slides down onto the shaft almost the depth of the shim in the above pic (I had to dremel maybe 1/8" off to avoid it sticking out the underside of the shift knob when installed). This ultimately creates a sort of poor man's short shifter, as the knob sits probably 1-2" lower than the stock knob.
Big thanks to Dave Mason for the great work. The new knob just further reflects how tired my shift boot leather looks.
Here's a couple more pics:
