That's a spittin' image of my alto (also 254XXX), what we call a transitional model, for all intents and purposes a 6M. Great horn, and it looks to be well cared for. The lacquer looks like it could be original, but do be advised that in those days, lacquer was in its infancy. Some folks bought a bare brass horn and had it lacquered afterwards. The case looks like it's not original. Value? For an idea of what it's worth, try completed items on e-bay. I paid $1,100 for mine, freshly overhauled and with worse lacquer than yours. (Just fyi, it took the place of my Selmer mk. VI- it's that good!)