I also have one of these heads, but I never used it.
Jim told me it was £100 just for the welding. But that might have been his price to Charlie, not retail.
Charlie said about £450 to do the throats, ports, matched to both manifolds, skim, seats and valve backs to three angled. (Same as Lloyd Bush who did the 11.9 second pass)
Plus I had the springs seats lowered and longer firmer new springs and custom caps fitted to go with a 12mm or so cam, eg, Piper 285.
Plus I was having the block and liners skimmed as there's quite a big error in those; you have the head skimmed but the block and liners are worse!
I stopped there though due to lack of health and money and didn't get the block done and 6 years have since evaporated