I agree, but you may want to consider the Rainbird 1800 Retro. It replaces one of your heads, and has a self contained filter and pressure reducer. Theyn just cap off the other heads. Often, on my conversions, I might use two or more on a zone, if I need 1/2 line at other locations. At $14 or less they are relatively inexpensive, neat and easy. Available at this sights sponser,
www.sprinklerwarehouse.com , and your local supplier
Jeff