I have an after-market service book covering L, LA, LI and some LU. For the Deere engine, (not the Hercules) there are no head torque specs, only "Tighten capscrews evenly, from the center outwardly until all are tight."
That after-market book also contain a reprint of the "Hercules Operator"s Handbook for NX Series" engines. That lists "wrench tension"s of 504 inch-pounds for the head. That"s 42 foot-pounds.