I think that the open driveline is simpler to work on and therefore better.
It is also easier to swap other stuff later like a different rear, or trans, or engine with trans. With a closed you can only use the original rear with a 3 or 4 speed.
So, if you ask me I would say go open.
But it is not quite so simple, you have to remount the rear to the springs and get rid of the torque tube probably by changing the entire rear.
So to go open leads to more than just a transmission swap...
What do you want?

•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-