When we did the gasket last time, we found that there was a few lose headbolts on the rear of the head and there had been work done to several of the hydraulic lifters as well, some where obvioulsy different that the others, maybe new or second hand, we just dont know.
So the head gasket, if replaced again would be the thrid time as far as we know.
After all the cost, and time involved in replacing the head again, such as Skimming, if possible, may have already been done before, pressure testing and new bolts, head set and labour and still no guarantee it will be all fine and dandy.
Then a second hand engine would be my prefered choice, anywhere from £100 - £200, plus hoist hire and a weekend fitting.
Or like I also said, a New truck for £400-£500 off Fley bay with MOT and Tax. Should be able to make a good one from all the parts of two trucks.