Yes the PO must have had work done as he could not undo the LHS exhust nut, so they cut it off !!!!.
It now has a neat little set up where it all just slots in and is held in by the little allen head screw you can see in the pics above.
The valves had burnt in as far as they could

so I just got to them in time, the one one the RHS head was just starting to hit the piston recess

.
I had to remove some of the resulting warped metal from that part of the piston with a scalple :-/.
The piston tops had tons of carbon on them, it was thickest on the bottom of the crowns.
So now I just need the gaskits to arrive from WA and I will be cruzin' 8-).