my 2 cents, drain the fuel system completely, tank, pump, valves, carb\injector,,,, everything that comes in contact with the alcohol. I fill the lines, pump, injector hat, valves,,,etc with marvel mystery oil including some down the supercharger. Spin it over by hand and let it get into the cylinders.
as previously stated alcohol is very corossive. I had a fitting loose it sealing edge even after above mentioned "winterizing".