The female threads do matter in determining the torque. If the hole is threaded into cast iron, I would not exceed 30,000 psi stress in the bolt, no matter what grade the bolt is. And, for a machine like this, I would strongly doubt that they would go to the expense of using Grade 8 bolts. Grade 2 is probably a better guess. I would use 4 ft-lbs, oiled.
For charts of what UNBRAKO felt in 1996 were reasonable tapped hole thread engagement to achieve female thread strength sufficient to achieve full tensile strength of a quality socket head capscrew into brass, aluminum, cast iron and mild steel, look at page 66/68 here -
Note their comment on page 64/66 about attempts to compute lengths of tapped hole thread engagement and related factors "by formula" being "not entirely satisfactory". Thus what they chose to present in the technical section of their "engineering guide" were tables created using empirical data from tests done with non-digital threaded test pieces, real bolts, and torque wrenches of some type. Seems like something that could be confirmed pretty easily if I doubted UNBRAKO's credentials or intent, or feared typos had snuck in.
