Now the really interesting part. A Locktite rep saw this post and contacted me. (Thanks Lindsey) Very interesting long chat. He confirmed that a test setup would be best but mentioned that the low viscosity Locktite products were deliberately engineered not to be too lubricating so as to not screw up published torque values. He said that they behave much like a very light SAE 10 machine oil with a k value of around 0.15 plus or minus. He said that the more viscous products are more lubricating. He said that if the common low viscosity products are applied on the threads only, a torque reduction of about 10 -12 % is about right. The thicker stuff that I am contemplating is between 15 and 20 %. (This is from dry bare steel, not plated steel.) He also mentioned the fact that it is poor practice to tighten Gr.8 and stronger fasteners dry and confirmed the corrosion potential in threaded fasteners. It is a big issue in the oil and nuclear industries.
Tonight I welded a 1/2" Gr.8 bolt to a piece of 4130 the same thickness as the engine mount. After tightening it once to allow the threads to make friends, I repeatedly torqued it to 58 lbs and measured both bolt stretch and angular rotation. I then applied low strength Locktite to the threads only and torqued to the same bolt stretch and angle. Voila, 51 pounds.
Great forum, (I found it restoring my SB lathe and Mill) and thanks for the great replies. Hope you find this interesting and/or usefull.