Are my head studs stretching? KZ305

I'm putting the head on my 82 KZ305. Following the toque pattern for the eight head nuts, I get them all tightened down to the recommended 18 ft-lbs. Then when I re-check them, following the same pattern, they start moving at around 14 ft-lbs and turn about 30 more degrees untill 18 ft-lbs is reached. I repeated this 4 times. Could the head and base gasket be compressing farther, or are the studs stretching?

These aren't stretch bolts (hence the need to "re-torque") I would be a little cautious that the studs aren't pulling out of the crankcase like "corks from a wine bottle" (I have had this with a CB1100 !!)

In light of Wookie's comment, could this be why you are needing to replace it again already? Seems like you did it fairly recently.

As did I, and I think mine is leaking too. More like sweating, no drips but it looks wet. But since it won't even start with my new carbs I've pretty much given up on it and am concentrating my efforts on getting my gifted 650.

This is the 3rd time in the past 5 years, that I replaced the head gasket do to oil leaking. However, this time I was able to source a NOS OEM head gasket. The first two times, I used gaskets from after market gasket kits. Time will tell.

My concern of head studs stretching was a false alarm. This morning I marked the position of each head nut and found they moved slightly before reaching 18 ft-lb of toque, but would move back to their origional position when the toque wrench was removed.This movement made me think the nuts were screwing farther onto the studs, but there must be some spring like twisting flex in the studs.

Exactly!  When you apply a tensile force to a steel rod it will elastically stretch a bit.  When you release the force the rod will go back to its original length.  The same thing will occur when you twist a steel rod.  It will rotate slightly and spring back when you release the twisting force.    If you apply enough force the rod will begin to plastically deform...growing permanently longer, but don't worry about that happening to your studs.  You would not reach that level of force unless you had a press.