If you have the proper tools and the intake manifold is not installed, you can measure your preload. It should be somewhere between 0.02" and 0.06 inch in most applications, though I don't have a Ford manual in front of me. If you have an aftermarket cam, suggested preload should be listed in the cam's documentation.
You can also adjust with the engine running, if you get (or make) blockoff clips to prevent oils spraying all over the place. Basic procedure is to tighten all rockers until they stop clattering, then loosen one at a time until they start making noise, then retighten until it stops -- this should be zero lash. Give it another half turn and it's set.
If what you have is actually a later non-adjustable pedestal type rocker mount there will be a torque spec for that mounting nut or bolt.