[SeaSlugs]

crank for awhile and see if the plugs are wet. If it doesnt fire after repeated attempts you should smell raw fuel.

If plugs are dry then you have a fuel issue. Did you remember to turn on all shutoff valves? electric valve actually opening up if present?

carb set to a basic starting range (gav 1/2 turn open idle air 1.5 turns open)

when you say good spark is it nice bold blue?

pull the spark plug straps leaving an air gap and see if you have spark out of the distributor body.

when you put the carb back on did you shove the line all the way into the carb?

even old fuel eventually attempts to run (poorly) unless its several years old.