Welcome to the Brotherhood :-).
JMHO: build your 6BR on a Short Action. There are advantages to putting the longer short action chamberings into a long action build, but not something as short as a 6BR, IMO :-(. You can do it, especially if you go single feed, but you already mentioned a magazine. I even shoot my long chamberings on short actions, but I am strictly single feed only. 6BR on a long action would not appeal to me. Again: JMHO :-)
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