you should have a higher compression motor, a head cut for it, and have the carb set up for it. also you should use better fuel lines, alky likes to eat rubber.
depending a lot of factors, may need a higher capacity fuel bowl, high flow petcock, and of course going to need good fuel line, the rubber will get eaten up by the alky
you also need to make sure that the premix you're using is alcohol compatible
methanol, compression must be increased and timing advanced. you cant really jet too rch with methanol, but its EASY to be to lean. you will burn about twice as much as gas. you will need to flush the tank carb fuel lines and run the motor on gas afterwards as the the methanol will eat seals, fuel lines etc. It does smell good and makes more power but its a pain in the ass and you will burn a lot of it.