Should go round to some wreckers and find out if they have any heads of wrecks. Ask them if you can take it and get it crack tested before you pay for it or if they'll refund if its cracked. It is an alloy head in the xf isn't it? I have been looking round wreckers and picked up a 3.9 head for an ea for $100. but it was tested and found to be cracked so i got my money back.
Thats one way out. A changeover head would have cost me about $500-600 so the wrecked one was the better way out for my....
EA Fairmont Ghia : 3.9L MPFI, 2.5" cat back sports exhaust, K&N panel filter. Pioneer head unit, pioneer 4" three way fronts, Pioneer 6" 3 way rears, 2x 12" subs, blue interior light.
My main pride and joy : '76 XB Fairmont GS, 250CI, 140,000 Km and all stock.... for now! (Factory air-con on the way)