sorry, didn't mean to make you feel bad. actually was thinking about the guy working on the car.
ok, first you mentioned rocker arm shims. what is that? what is
trying to be accomplished?
the only shims i know of are for the cam bearing towers for
a warped head. the only other is for the valves. the caps that
the rocker arms rest on. this is for keeping the valve adjustments
near a middle.
if the chain is loose then something is wrong. period. shaving the head will not do this.
when you shave the head you need to check the valve timing and
the safety clearance.
after all this then you can play with the timing. if the dist is worn it can adv timing to fast or give you a hard time timing the engine
at idle and in gear.
you need to start with the chain before all else.
there is a possability that to much was taken off and nothing will help.