Hi Derek, Peter, Gale,
5 ft/lbs on the four outer studs is enough to keep the head gasket seal, how do you measure 5 ft/lbs when you are slackening the nuts, and you have a torque wrench that reliably measures 5 ft/lbs?
Measure the 5 ft lbs with an in lb torque wrench (60 in lbs)
Like 'prt seal crush', because Dave dared to post an actual figure isn't a reason to overthink this - it doesn't matter whether the figure is 4 ft.lb., 5 ft.lb. or 6 ft.lb., what matters in Dave's method is keeping a little tension on the outer head bolts
Fwiw, I've done the procedure outlined by Dave numerous times, usually simply to change a leaking rockerbox-head gasket; when doing this, I've only ever removed the 5/16"UNF bolts or studs through the given rockerbox and haven't noticed any warping of the head.
If you have to remove both rockerboxes - if changing the tappet adjusters, say - don't bugger about, just undo all the head bolts as directed in the manual
, dissemble, change or anneal the head gasket along with whatever else you need to do and reassemble; life really is too short to agonise over how much tension to keep on a couple of triple head bolts ...