It looks like you should be able to use your original rear shaft and carrier bearing.
The front shaft you would need shortened to work with the new transmission.
Then double check the geometry and shim as necessary to make the angles right. http://www.stovebolt.com/techtips/driveline/setup/index.html

For a two shaft system the first shaft needs to have it's centerline 1 degree down (or up) in relation to the transmission/engine centerline. With that 1 degree the inboard yokes on that shaft need to be in the same orientation. The rear axle pinion centerline then needs to be parallel with the centerline of the first shaft.

Grigg

•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-