[Coley]

...plugs look like a mix of brands and not the original sizes.....
Sounds like your basic parts group otherwise is in good shape so far....but you have some troubleshooting work to do.
I think the 15 inches of vacuum is probably ok, depending on what rpm you were at.
More important was the 'needle behaviour'...ie: steady? bouncing? intermittent drops? or?
...do the timing first....as Geezer said, bump it up.
Then I would look like mad for a vacuum leak somewhere....brake booster?...intake manifold?....carb insulator gasket?....open port or line?....broken vacuum hose?
...more pics?

All good
Coley