I like to use a torque wrench to ensure even tightening and to avoid over tightening....The M20 has 10 off 3/8" diameter BSF head bolts and by comparing to more modern engines with the same diameter bolts (which did have a torque setting) and with a little experimentation I arrived at 28-30 ft./lbs as a practical setting for that engine...Ian
As you say Ron it doesn’t have a head gasket, yes he has lapped it.
I suggested around 25 lbs( close to Ian’s Figures) but A no gasket to compress and B can’t get a torque wrench on the bolts.