How much rust is there on the 1950?
Does the 216 in the 1953 run?
Did you find the block-date and head-date casting codes on the 235?
If I had what you have AND I could only keep one truck, I'd probably put the 1950 drive-train into the 1953 truck and swap the 1953 drive-train into the 1950.
What did you pay for the 1950?
What did you pay for the 1953?
The drive train in the 1950 is not stock GM: the 235 was not a factory option in the Suburban in either 1950 or 1953, and the truckstell over-drive is a non-GM part (but, it is a very nice part). Those parts would be just as rare (and non-original) in the 1953.
If you keep the 1953, would you want to keep it "original"?
Do you have one full set of seats (at least) between the two of them?