HAVE A 1989 F-150 WITH A 351W IS IT WORTH THE TIME AND MONEY TO PUT A SET OF ROLLER ROCKERS IN AND IF SO WITCH BRAND IS THE BEST ???

If the engine is otherwise stock then the answer is NO.
Just tossing on a set of roller rockers isn't a very good idea unless you make sure and match the cam, valve springs, and timing to get the maximum efficiency.

if you are takin apart the motor any ways do it. you will be happy with the results. you will be unhappy if you just pay to have that alone done.