Rare Dodge Dart GT? Which engine is this?

I agree with what someone posted a few pages back, I have a feeling the original high-HP engine that hung with your dad's GTO was swapped for a "tamer" V8 at some point. Unless I missed a post where you confirmed it still has the original engine from that time @heavnxbound_

With that said there's no reason to think any less of the car. Chrysler small block V8s make great power with minor upgrades. Even if it's the smallest version (273) that would be one hell of a fun car with a decent camshaft, 4-bbl intake manifold and carburetor, and dual exhaust (which I'm guessing it already has?).

Anyway let's figure out what you have first and go from there. Also welcome to the forum!