When lashing valves with new hydraulic lifters, its very easy to make the mistake of going to zero preload instead of zero lash because the spring in the lifter that holds it up in the absence of oil pressure is very light. What then happens, is another half to one turn is added, and the valve hangs open.

For that reason, I don't like spinning the pushrod to "feel" for when the lash is at zero. I like to jiggle it up and down until lash is gone. You may already know this, but thought I'd share my experience with it.

I have also found a lot of builders like to drill small holes in the front oil gallery plugs to lubricate the back side of cam gear, that will also starve the top for oil, it works ok with roller rockers in most cases , but not stamped steel, with a roller tip. Good luck

All the mercury performance engines and possibly all BBC have a hole in the front plugs stock.

Definitely completed the initial adjustment with the spin method and had a gut feeling that it was too tight. You live and you learn. I will be ordering new lifters for sure. Small price to pay in my opinion. I am hoping the rain holds out this evening to get it disassembled.

"FYI. I am also going to check out the lubrication system as it is apparent that there was a lack a lubrication at some point while running causing the damage and carbon on the components. "
Not necessarily a lack of lubrication, the heat could also have come from the parts in the valve train making contact when they are supposed to be separated by a film of oil.

I agree. I would use a moly paste (like flat tappet break in moly paste) on the balls/sockets. I never liked the idea of regular engine assembly lube here. It is not a bearing !

But, I never bought into steel rockers (or roller tipped one's) unless restricted rules racing (sbc's) forced you. [But, we'd keep more oil to them with 'Kool Nuts.'

I like use a good assembly GREASE on that stuff.

I agree with your statement all plugs have a hole, very small hole. When engine builder hot tanks block and replaces plugs , they re drill a new hole and sometimes it's to large, and starves the top end for oil with a stamp steel rocker, full roller rocker requires less oil, then a stamp steel.

I used those rockers ONCE, gen 6 502 with stock cam, lifters and springs. At 120 hours when I tore it down to freshen and upgrade it most the rocker balls were galled blue and rockers were burnt. One rocker ball was split in half but miraculously hadn't came out of rocker. Never again, I used them because I was on a buget and thought it was the only thing that would clear stock valve covers (NOT TRUE). A local engine buildr also used them on a Pontiac, the oil holes were located wrong and oil would shoot out of them miissing the spings and rocker balls, they turned blue on dyno and were vaprizing the oil, literally had oil smoke coming out of valve covers because when it did hit them it was almost on fire. Never again, only time I know of anyone getting them to work very long was on sbc circle track cars with kool nuts, fwiw, Smitty

And don't put that plug on the back side of the block by the freeze plug...
It will make a mess in the shop when you prime the it!