With enough time and money that 216 can become a 258 cubic inch engine with pressure-lubricated connecting rods and a much higher top speed capability than it has now and still look "original" from the outside. However, it requires the services of a mad scientist machinist- - - -and there are very few of us left on the green side of the grass these days. If you can find a rear axle with a 3.55:1 gear ratio for a 1950-53 Chevrolet car with a Powerglide automatic transmission, it can be modified to fit the transmission on your 38 truck, and keep the original-appearing torque tube drive system. Bring money- - - -lots of it!
Jerry