Need help with my dad's engine!

has it ran decent since the rebuild?

I would suspect the timing chain to be a off a link

is it a flat tappet cam ?
you may have wiped a lobe

I'm not real sure on the cam to be honest. A friend of his rebuilt it and I haven't talked to him about it but it's a very reputable shop in cincinnati and they did break in so I am guessing he didn't screw anything up. It didn't do it right after the rebuild that I know of. It started a few weeks ago and he drove it home to work on it. After taking the ignition apart he drove it again and it still did it. That's when he replaced everything then drove it again today I am guessing since he called and asked me about it some more. I told him to throw one of my Holleys on and see what happens but that was the last I heard.