replacing 2000 4.0L head

I have read the threads about the 2000 xj having weak heads and I am pretty sure mine is cracked. There is no oil in coolant but the oil cap has greenish muck all over it, my coolant was slowly disappearing, no water through tailpipe, the dealer tested compression and CLAIMS all cylinders good, no low oil pressure. I never overheated it to redline but I bought it 6months ago w/50k miles. Is this a cracked head and if so what year head will be compatible with the 2000 block. I greatly appreciate all the knowledge that passes through this site!!!

I need to get this fixed asap so I am willing to pay if there are any xj experts with time in Ventura area, and maybe a spare head or whatever it needs. Thanks in advance