you will need to fab. a new bracket if it is a factory switch. the factory switch is a very hard to find item for concorse guys, worth about $250 in good working condition. If you don't care about that kind of stuff they sell a aftermarket switch that will work. You can do a search for TH400 Kickdown switch and all the info you need will be there with pics.
1967 Firebird: 326ci, Holley 670cfm street avenger, RPM intake, Headmann headers, HEI