Hi Chris, I would be afraid of compressed air and those old seals but we used to just fill the pump with gas and gently move the cam arm on the pump until gas comes out of the outlet line to the carb. If it squirts out go ahead and install it on the engine, start it up and watch carefully for leaks. Hopefully it will be ok but keep that fire extinguisher handy. Compressed air was usually used for blowing out the gas line but do not have the fuel line hooked up to the pump when you do it. Too much air pressure can do a lot of damage.
