What I do is apply torque to accessible bolts while bringing lower ones up with end wrench. Keep the wrench the same length as your torque wrench so you have the same amount of leverage. Then concentrate on your pull and duplicate it as close as possible. I have been doing it for 45 years and have grown quite accurate. The key is to feel the wrench on the upper bolts that are very close to torque and duplicate that pull on the lower bolts. Make sure threads are clean and very lightly coat them with anti-seize, making sure that no compound spills onto the gasket surfaces. Put a lite dab on the head surface where the bolt contacts. This will all add to the accuracy of the torquing job. Be sure to replace the water jacket gasket on the head as well, they are likely to fail too, especially if not glued with permatex. Of course the head gasket goes on dry, however.