It may fit if you set the cab above the frame.
Knowing the original frame is 36" I'm sure a 46" frame won't fit in the same place without trimming at least the back of the cab/corners.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-