All good question above, I can add a few.
Does it try to fire if you dump a little fuel down the carb?
Are the plugs even firing? pull one out and lay it across the engine to check.
Is the starter really hot? or just burning grease and oil out of it?
Have you pulled the plugs and spun it over with oil in the cylinders using a 12 volt battery?
Do the rocker arms have oil up to them?
Have you tried a small fuel jug instead of the fuel tank?
Have you rebuilt the carb? Its a must for a old engine!
Joe