318 magnum VS 318 roller VS older 318 gas mileage

Technically the non roller LA would be the worst.
So Magnum vs roller La both have roller cam (less friction) and closed chambers (better combustion) that leaves head ports, La are smaller and would help with VE%
So the LA roller should be better but in reality the there probably little to no difference in mileage .Saying that I would go with the Magnum better flowing heads will make the most power per mpg.