With 13 7/8" on the wood I would opt for the butt plate. If you decide on the pad I would recommend not cutting the wood which would hurt its value a bit on a resale. You might find a used butt plate on ebay that would work but repro's are available and are easier to fit. 1915 was kind of a transition period so either the early Flues or the later Flues butt plate would be appropriate.