Wrong end of the country to help you, but there is a 4x4 shop near me (near Seattle) that narrows big front axles for rock crawlers. That guy could do it and I'm sure there are shops in the East that can also.
As for putting a '39 on a modern 1-ton frame, I believe it could be done.
Click this link and look at the picture.
http://www.oldsub.com/images/2006/08/26/100_1437.jpg I didn't put it in the post because its too big and I'm lazy tonight, but what it shows is a '36 Chevy 1-1/2 ton sitting on 1-ton running gear. yes your '39 is different in a number of ways, but front track isn't much different.
This guy widened the front fenders to fit over the new front axle. You can see the steering box above the bumper and if you look in the folder
http://www.oldsub.com/images/2006/08/26/ at the pictures near the first link you'll see more detail of how this one was put together.
This particular truck was Diesel powered and was displayed at the ATHS show in Brooks, Oregon, late in August.
