My thoughts:
Verify the distributor is advancing ( that is - that it isn't locked or a spring broken etc. ) MSD distributors come with heavy springs and have adjustable advance via replaceable springs and stops, they have 19 degrees advance and aren't all in until over 4000 from the factory IIRC. Ive seen the lighter springs rust and break in long term storage.
The cam card - get it out. Get out your cam degree kit verify the events. (you will verify the timing marks in the process)
What is the IVC at advertised on that cam, because the 050 events and 12:1 (or 11.5) static sounds like a recipe for disaster to me, but a few degrees could make a huge difference in dynamic.
If you don't find any issues there, you're gonna need to check compression on that last cylinder, look for broken valve springs and stuff like that... Is it a Hydralic Roller?