I checked the spark on my wifes car (4 cyl but...) and they look similar. I wouldve expected better from the HEI distributer but. So I guess spark is okay.

I did try to cover the carb slowly with my hand- Doing this speeds it up a little but still same reaction when shorting the plug wires. I expected it to speed up a bit but it doesnt smooth out at all. can still hear a miss.

A guy at work suggested tighening the rockers a bit more. Even if lash is good, if the tips of the valves or pushrods are worn it may not be openong correctly. I'll give it a try but will only run it long enough to see if it helps.