My current 1200 is my third. I bought it in 2001 to replace my 2nd 1200 which was t-boned. I bought that in 1991. Car is sitting in garage waiting for engine rebuild.
Not as active on the site anymore. I still check the front page almost daily and read whats interesting.
Regarding the rocker tip damage, I had this happen to me and was told it was due to valve float. What do the valve stem tips look like? Are they damaged also? Have you confirmed the valve springs are not stacking solid at full lift?
Regarding the scoring on the ID of the rocker arm, The last time I assembled my cylinder head rocker arm assembly, I noticed that I torqued the rocker tower bolt too tight and the rocker became too difficult to move by hand. Basically, I was crushing the rocker shaft and it was not round. Luckily, I loosened the bolt and retorqued and all was well again.
Oh boy, I might have something mixed up regarding the black cartridges in my picture that I have labeled as "KYB 361005". I may have mixed something up on my end. I'll have to check it out.
Here are some old pictures that might give you an idea of what is inside and how thick the walls are. This is an old A12 head that I cut in sections on a bandsaw.