[56markII]

As others have mentioned the nuts in this case should be lubricated with a good heavy motor oil and if you don't have a diagram showing the torque pattern, years ago one instructor told us that torquing a head gasket is like spreading out a piece of paper! He told us that if you don't have a pattern in a shop manual, a circular pattern spreading outward will work. Start in the very middle and move from bolt to bolt in a clockwise circular pattern. Don't start on the ends but instead start in the middle and work your way out! A much lower torque at first and higher in steps until the final torque. When to retorque? Cast iron heads you bring the engine up to normal operating temperature and then retorque hot. Aluminum heads you bring the engine up to normal operating temperature and allow the engine to cool to room temperature and then you retorque. Aluminum expands at three times the rate as cast iron and retorquing while fully expanded is not good.
As Pete mentioned the threads MUST be clean! If they are rusted and dirty this will cause drag and give a false reading fooling you into thinking they are tighter than they really are. They should turn freely or glide as you turn them and clean, lubricate and turn with fingers until they feel right and if not repeat until they do! Don't forget to lubricate under the head of the bolt as well. When the torque increases there will be drag between the bottom of the bolt head and the surface of the head, washer if used and the bolt!

There is never time to do it right but there is always time to do it over!

PS
Make sure the surface of the head and block are also spotless and clean of rust, dirt, any gasket material as well. A razor blade scraper works good as well as a fine sandpaper using your finger tips until a shiny surface is obtained. Roloc pads are great but don't stay in one spot but keep moving so you don't damage the surface.