5 minutes ago, Zed Head said:

How about a shot of the bottom of the cylinder head?  You can stand them on end, they'll balance.

Seems like somebody over-revved, or had some stuck valves in the past, or didn't get their cam timing right during install.  The dings are covered with soot so they're not fresh.

Check your cylinder head number too, see if it's an N42, that would have come on a 75 engine.

I'll be sure to upload more soon. You'll get to see a chewed up cam bolt (definitely was not torqued down either!), healthy amounts of orange RTV, and soot... lots of soot. I do recall it is the N42 head. I'll take more close ups of each cylinder, walls, and valves too. I'm starting to get the "while im in there" syndrome.

My suspicion is the same as yours with the over-rev. With how cylinder #3 rocker jumped on the lash pad, it seems like an ideal case. 

Stock EFI is not very tolerant of changes!

Lash pads jump off rockers.

It's happened to me before and I almost crapped my pants. I was a long way from home putting some miles on a fresh rebuild. Babied? babyed? carefully drove home and got it back on. Never happened again. Thanks @Jeff G 78 for helping me with that.

2 hours ago, Patcon said:

Stock EFI is not very tolerant of changes!

Yea, thats my main worry going into it. Maybe I'll stick with a good freshen up for now and worry about cams if I go with a stand alone.

I created a new thread to track the progress going forward: