If you have too much
oil up top, and you have no restrictors whatsoever, then you probably need them. On the FordFE forum there has been a long standing debate over the size of the restrictors though. There was *almost* a consensus at one time that .090 on a hydraulic setup and .060 on a solid setup was generally appropriate. A search of the forum will bring up many posts on the subject along with other factors that can help on the "too much
oil up top" issue (smoothing out the drain back holes) and add-ons, such as roller rockers, that might reduce the need for
oil up top as well. FWIW, I have .060 restrictors on my 428FE with a solid flat tappet cam with roller rockers and aluminum heads. Here's a link to a thread that I'd forgotten about where one fella is recommending .070 restrictors.
http://www.network54.com/Forum/74182/thread/1140835392/ Changing them is not major surgery, so you can always start large, and then restrict, until you find what suits.