It shure won't hurt anything but I think it's not needed as thats what the solenoid on most GM starters is,they don't take much juice at all so unless you have a super wimpy starter button or plan to do a lot of serious starter crankin I wouldn't worry about it,
no reccomendations from the MFG of your switch box? Same deal with the ignition box,how many amps required and what's the switch rated at? Of course the ignition will be continous where the starter is momentary,check your specs and go from there,Later