grab that rocker at O lash see how far you can move it side to side looking at the roller tip and valve stem see how far it can track side to side on the rocker and check to see if it can hit any thing when you move it .i do this and if way off some times you can move the guide plates a bit or go with adjustable .still even running off track still should not make more noise less the body is hitting some where.as for checking for a sticky valve you have to get the valve spring off .there ways to go about this take plug out put air in the cylinder get a spring tool .and set up a test spring move it up and down by hand see if it sticky .for getting the lifter out it is not a big deal a 289 with a roller cam you have to pull the heads to get the longer body lifters out