The shorter stroke looks like a way to increase RPM (and it is, in terms of wear and life expectancy).
Since all of the head castings are pretty bad by modern standards (or even 1951 standards: Chrysler 331), reducing engine size improves VE.
However, the stroke difference isn't that much (4.7%), and at the same level of tensile stress (assuming identical component weight, etc.) it's a very small advantage.
Using 90,000 f/s/s as an RPM limit, the 228/248 reaches 6,373 RPM, only 184 RPM higher than a 270/302 (3%).
