[Mike Taylor 3601]

I buy zinc alloy from Mc Master-Carr industrial supply, about $40.00 will do 2-3 sets of heads, melt it with a acetylene torch into a steel container with handle on it, I made one by welding piece of tubing to flat bar, bolt a plate over intake side of heat riser passage and pour from exhaust side I use a small metal funnel and extend with tube if need reach deeper to heat crossover.
I fill crossover up within 1/8-1/4" of exhaust port,if you overfill can tilt head and pour some out or if sets up on you before you can pour out can turn head over and melt some back out or clean up excess with torch.
zinc alloy will stay for years and years.
Mike Taylor 3601