From everything I have read, the Ranger roller cam will not provide a noticeable difference in horsepower. It is a good reliability upgrade, chance of wiped lobes is greatly reduced.
The 94 Ranger should have a roller cam if it is stock. Some where between 94 and 95, Ford went from 11/32" valve stems to 7mm. The 7mm rockers will not fit over the turbo head's 11/32" valve stems without machining/grinding. The 7mm roller rockers are identifiable by their stamped metal construction versus the earlier 11/32" roller rocker's cast construction.