What is a B-50 other than an upgraded B-29? This is the 1/144th Fujimi B-29, but I recommend the Academy kit for this project. Why? 1) It's inexpensive; 2) it's easy to find; 3) the parts required scale out correctly. (and don't throw those unused wings away!)

The B-50 used the same wings and tails as found in the Academy Boeing 377 kit.

Use the B-29 Fuselage and horizontal stabilizers. Apply the Boeing 377 tail with a cut out for the tail gun. Use the Boeing 377 wings, but cut off the part that goes INTO the fuselage of the original kit. Add the 377 landing gear and the props without spinners, and the B-29 kit guns and bubbles and viola! 1/144th B-50