Definitely old stuff (the clear plexi mini-knobs are the giveaway) and there's no question that it sounds great (old DeArmonds generally do), but the cardinal rule is that you
never, EVER cut/drill/screw-mount
anything into an acoustic carved-top instrument - the serious postwar jazzbox players all understood this and adopted the "monkey-on-a-stick" Rhythm Chief or FHC, which left the top unmolested and maintained the guitar's full acoustic properties. I'm thinking this one was owned by someone who made a half-hearted attempt at learning to play right about the time Elvis got out of the Army (probably got talked into the pickup at the same time as you suggest, by a store owner who wanted it out of his shop ASAP -
for obvious reasons) and packed it away, never again to see the light of day until it found its way into your hands; needless to say it's your guitar/choice, but if it were me I'd remove that pickup, have my tech fill and spot-refinish any holes left behind, and sell the otherwise excellent-condition pickup to a collector for historic value alone - might net you a couple hundred to offset the cost of repairs, and I think you'll see a
major improvement in tone and volume...
