I had to replace a head gasket. When installing and tightening the pushrods and rocker arms, how do I get each cylinder on TDC in order to tighten the bolts to spec. According to my manual it says you can break parts if trying to tighten the bolts when valves are open. Is there an easy fix?

If you have the Haynes manual, it explains how to do that. Look at the section on finding TDC. I'd expect Chilton the same. I also find Autozone.com to be very helpful in their repair section.
For each valve, rotate the engine until the lifter is on the base circle of the cam (valve closed) for each rocker arm as it is installed. For the final tightening, the camshaft may be in any position.