RE: m48 mauser rebarrel
I dont quite understand your question, if your wanting to change the caliber you need to change the barrel unless your wanting to wildcat it to 8mm-06, then you would need to make sure it has a barrel bore of .323 or you might have a high presure issue. Your best action would be to wait until you have the rifle, then take it to a competent gunsmith to make sure it is a good action worth building on.