Vibrations / Shaking / low power

Thx a lot...
During restoration all was renewed, new spark plugs, distributor, cables, sensors, thermostats, hoses. We sealed everything. My mechanic had the Dodge manual in front of him and tried to follow the official instructions.
If this problems would be at a Mercedes or BMW engine, I could fix it drunk, blindfolded, with my hands tied at my back. But american V8 are unknown territories, a new land.... I even wouldn't see the difference between a stock and a modified camshaft.
Next week I will sit with my mechanic and try to follow your instructions - maybe we will find what's going wrong.