1969 instrument cluster in a 1967

[cj847]

Every time I drive my 67, I pull the darn wiper knob off thinking it's the headlight (my other truck is a 71).
Anyway, I would like to put a 69 and up instrument cluster in (or at least the outer cover). The wiring is not a problem, but the light switch mounting hole is. The upper hole (currently for wipers) is 1/2" dia with a flat across (same as choke). The headlight switch hole is 7/16" with a notch to keep the switch in proper position.
I plan to just hack a slot in the bottom of the 1/2" hole and drill enough of the flat off to get it perfectly centered in the instrument panel. Just checking for better ideas from someone who's done it.


PS> the 3 holes other than the headlight hole are all the same shape