LS Swap '65 Valiant

As far as modern power goes. I think the LS would fit the engine bay of the early Mopar better than the Gen 3. The Gen 3 engines are wide motors. The LS are narrower, maybe narrower than LA. The GM overdrive transmissions seem to be smaller around the torsion bar cross member. I think the little car could be capable of better mileage with the LS series engine.
So. I could see the reasons to consider the swap. I think it would be entertaining. Maybe in a weird sick way. LOL
I would keep it Mopar powered if it were mine though.