I was in the same situation last year, the head gasket went and it had about 105k on it.
I decided to get a full standard rebuild with group a gasket, it was the best thing ive done!
It was so much better after the rebuild, made me realise how tired it was. Now its stage 1 and pulls like a train

Look at it this way, its not a cheap job to the the gasket done, and having that amount of miles on it, its only a matter of time till it needs a rebuild anyway.
Then he will have paid for the gasket to be done for nothing as it all has to come off again...