Boxhead,
It would be easier to chamber the 99/44 Ruger deerfield in 50AE as they have the same rim and over all length.
My question, not having taken the stock off of mine is how is the barrel attached and how hard would it be to be able to just swap barrels and mags? Are the barrels held on like the 10/22 or the 77/22? I think the old 77/44 the barrel is held on that way as well and it would be a better start. The down side is will the 77/44 reciever be able to take the stress from the 50 AE. And then you have the whole mag problem.