Worn valve tips , valve action geometry and Mushroom head adjusters.

After a lifetime (or two)  of use the 1960  99 is making a few unexplained noises. I  will be investigating soon . In the meantime i have been gifted a set of Mushroom head adjusters (ta mate).  I know the valve tips are indented and the valves are from 1959 when the bike was built. So its likely that new ones are in order. Compression is still very good and  this 80 year old would be happy with less..  We know that the AMC factory  lengthened the valves and shorten pushrods to correct a long standing error in valve geometry on heavy twins  ,but they did not make it clear when the error was instigated. I had  assumed that only the DD head was affected , but thats an assumption only.  If the action can be improved on the 99 .why not?. I will be fitting a compression plate to assist easy starting and that will effectively shorten the pushrods , the valves will probably have effectively lengthened themselves with grinding in sessions and seat errosion  so its possibly corrected itself !.  This was the situation on our Atlas. The 99 has always been unexpectedly quick according to other members.  Anyway i can lengthen valves with RGM lashcaps and grind off indentation on old valves if happy with the condition . All that i need is a practical  routine to evaluate the valve /rocker action .  Suggestions welcomed.