Replace everything except the major hard parts (unless there is reason to). If you save $80 and don't change the timing chain and it breaks, you have to split the case again to fix it.
Clutch is an easy 15 minute job with the motor in the car, so if it looks fine, just run it.
As far as the head, as long as no problems are found, do a valve job and I would put in the APE heavy duty valve springs, they are less expensive than Yamaha ones, and better in my opinion.
Just make sure he has the manual and takes his time
