Well, I got my car running nice, and decided to quieten the rattly chains.
Did all the timing chain tensioners/blades and whilst putting the cover back on have completely mullered the headgasket. Tried putting a load of sealant on it but it's pissing oil out from the front between upper tensioner and cyl 1 exhaust port. I even tried cutting the old bit of gasket out and making a new section up, still leaks.

No choice but to replace the headgasket. I've done a few on various other cars (mostly fords) so not scared by the work just wondered if there were any special "gotchas" or tips people have for an X300 AJ16 head gasket?

The head bolts are too pricey so I'm intending to reuse them as have read in various places that's fine.