Why a toggle switch? Most regular ignition switches will carry the current for a HEI without a problem, or if you're concerned about overloading the switch, you could use it to turn on a continuous-duty relay triggered from the "run" position of the switch.

If you choose to use a toggle, a 20 amp should be plenty of capacity.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!