I can get about 14 or so with my 250 around town. On the road it will get 18 or 19 at 55mph, but at 65 or 70 it drops back to 15 or 16.
My 37 is pushing a lot of air at highway speeds, the front windshield is as flat as a barn side!

My '03 Toyota with its 3.4L V6 gets slightly better milage then the '37. Its a whole lot more aerodynamic and weighs about 200 lbs more.
But considering I pieced the old truck together, made my own intake, set up carburators (3 of them) off a different car, and set the tune up as best I could, I say the old engine is pretty good.

I am with PJ on this one. Old designs are not nearly as bad as most think the are or were.

In a head to head test, same speeds and payloads, I bet the old truck will hold its own pretty well!

Joe