i would use propane, or oxy propane but you will find yourself needing a lot of oxy. I have given up with it and just use plain propane in the red bottles now, gets plenty hot enough for lead
using a 15 kg (i think) bottle of propane from my local garden centre, rent free, deposit of 10 quid per bottle and 34 refil each. I have 2 and they last ages for me. I use them for heating and hardening, hot bending, if im desperate and need to cut something i link the oxy up, change the torch and job done. Also use them to melt any scrap aluminium in a small forge to make it easier to store and have even used it to heat the shed on really cold days