i have a 92 lx mustang with a long block from a 93? lincoln town car. the plugs are diffrent than the stock stang motor so i know there is a difference, but what i am not sure. it has a gt 40 intake, e cam, powerdyne blower. the rocker arms make alot of noice when the motor is running. i checked them with the valve covers off and four or five had a little play. do i need some kind of shims? i'm not sure what to do. the rocker arms are stock. any info will help thanks.  

The heads I am almost sure are E7TE's or E5TE's. The both will accept the same spark plugs. The heat range is significantly different though. Also the fact of having a boosted application will absolutly have a different spark plug. As far as the lifter/rocker arm clatter: You should be able to move the rocker arm back and forth horizontally a little. A quick way to tell if there is to much clearance, after running the motor pull a valve cover and try to spin the pushrods. Obviously when the valves are closed. If they spin freely then either the lifter is loosing it's ability to stay pumped up or the valve stem face or rocker arm slide is worn, also a worn lobe on the cam. The hydraulic lifter should take up the slack of wear and tear over time. It may be time for a valve job. Blown applications wreak havoc on valvetrain, due to the increased cylinder pressure to which the valves have to open against and higher heat. It is easy to check your clearance with a feeler gauge. Should bve anywhere between .018 to .45