Your family will love riding in "the old truck", too.
My '65 has a 250 6-cyl. and 4-speed out of a '74 car, and I'm getting close to 20mpg. I rarely exceed 45-50mph because I don't have to.
I'd love to spend a couple grand on it and make it really nice, but I don't have to. For now, it's just an old driver...but it's so cool!
Best luck.
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