When i converted my Charger from power to manual,,,,i had to get the correct "manual" plate for the firewall to mount the MC....
I got a used one from Tony Dagustino here on the board.....
I dont recall having to do any drilling....

I just pulled off the old booster,,,MC,,,push rod,,,,,installed the new "manual plate",,,got an adjustable pushrod ( or a rod for a manual ),,,and put on a different MC.....

sorry i dont have any pics.........