Restored d17 project

Not necessarily. But if the cam timing to the crank was off, it probably wouldn't ever run regardless of where the ignition timing was. Late camshaft timing would result in the exhaust valves getting smacked when the piston was coming up and the exhaust valves aren't yet closed.  This catastrophic failure of the valve train can only be from incorrect valve guide height. The cam/crank timing was correct. How could 8 valves be stuck in their guides?? very doubtful.

If the guides and caps aren't interfering and cam timing looks correct and guides weren't stuck about all that's left is rocker adjustment. So wait a minute...tall heads use short stands,short heads use tall stands...do we have short head short stands?

Here is a picture before I removed it.

In that picture it looks like #4 intake is the only valve that is closed. I wasn't aware of two different pedestal heights that SteveM mentioned, but I was able to find a picture on Facebook of a D17 engine, and it looks like the pedestal mounts are about 1/2" taller. It also looks like there is a color change on the studs about 1/2" above the nuts in your picture, like maybe that is where the nuts used to be. I learn something new every day.

Ted