As it is very easy to remove the head,I would do that and check the valve and bore condition.If you dont want to do that,then take out the sparkplugs,squirt oil in,refill the tank with clean oil,and crank the motor until oil appears in the top end,and returns to the oiltank.Check for spark[new battery?].Refill the gearbox and primary,put some gas in the tank[minimum amount]and see if the carby floods.If it holds fuel correctly,try to start the motor.I reckon the clutch would be stuck though.Regards John.