Yes, I believe that their six cylinders, and Hudson’s older-design engines, were the last to use that primitive technology.
Yes, Hudsons were very well-engineered cars. Their Nascar victories were the result of their superior handling, as well as a good amount of power.
Now that we have computer-aided design, I have read estimates that the Hudsons of the '50s could have been made almost 1,000 lbs lighter without sacrificing strength. Those cars were essentially over-built, just to err on the side of caution.