Do the WW2 manuals tell you to tighten the jeep head more than once?
It depends on which TM you look at. Maybe tightening the head more then once after installation was a common knowledge then for 1940s mechanics? At any rate, you have to have more than one manual with these jeeps. I found the answer on page 69, No. 18, TM 37-2810, March 1945.“Caution: Cylinder heads should not ordinarily be tightened unless there is a definite indication of looseness or leaks. If tightening is necessary, use a torque-indicating wrench and tighten in the sequence and to the tension specified in the vehicle Technical Manual. When a new gasket is installed, tighten three times as follows: First, upon installation, second, after engine is warmed up, and third, after completing final road test.”
For the WW2 jeep you would follow the pattern as indicated in the graphic below:
See Cylinder Head Tightening Chart for more info. You might be interested in learning about how to rebuild your jeep engine. This is covered in various collection of manuals but the original manual was TM 9-1803A Engine and Engine Accessories, Willys Overland Model MB and Ford Model GPW 1/4 Ton 4×4 Technical Manual. This manual is available as a reprint. Check it out.