You can drain exhaust manifolds (plugs underneath).
Crank the engine (cylinders) dry. Check ignition components. Put
little engine oil in cylinders to enhance lubrication. Clean spark
plugs. Carb and fuel pump as well as the tank has to be checked for
water (removed and drained) and cleaned.
It should start no problem. New fuel source may not help if water
present in the pump and the carb. This is your no. 1 issue.

Been there, done that !!!