He said he has a 5.8 (351) and the Dodge has the 318 so I'd think if anything the Ford would be a bit better since the Dodge is slightly underpowered. My Uncle has an '88 Ford with the 302 and although I think it's actually lighter than my Dodge I think it is worse for gas mileage. Thing is though, I've never done the numbers on his Ford.
Either way, I felt the Dodge was close enough in general to get a ballpark as it seems no one else has any numbers that closer reflect his unit.
Of course the higher speeds could also be a factor.
Cheers all!!