Don't wast your time retorqueing the head, even if it stops leaking it will restart!The leak is much lower than the rocker boxes, please view the attached pic. The engine has not been cleaned for a long while.
I will get a set of rocker box gaskets and retorque the front head bolts. Hopefully it will not be too much of a PITA to remove the front box.
Thanks for the advice on the service manual. I found a bunch of factory CD’s on EBay.