Awesome Video - Basement find 1970 Hemi Cuda...149 Miles and other Mopars

Since it started up right from the get go,I'd assume that they prepped the motor before starting it but who knows what happened before the video started.

That's an amazing find and personally I'd leave the Hemi in the Cuda since it's been in there since the car was practically new and was a big part of the cars racing past.Putting the stock motor back in would be like erasing it's history,IMO,kind of like putting the stock wheels back on instead of the mags and slicks and sanding off the lettering and artwork.
The GTX could be put back on the road with a replacement Hemi engine and just enjoyed like that.Lot of people pull their car's original engine and install a 'fun' engine that they can use as intended without worrying about accidentally damaging the numbers engine.If you owned both cars then you know where the original motor is anyways.