We use it for structural construction (including interior ship lap), but for guitar soundboards, it is way too stiff and too dense which could affects vibration, sound transmission and energy. Those posted would not make it as soundboards as they need to be axe split into quarters to prevent grain run out and natural grain separation. Plus they have to be perfectly quarter sawn and not quartered. The face grain already shows deviation and the spacing while it’s tight, it deviates from one end where it is on the fine tight to tight and to fine tight.
I don’t know how many board feet you have, but I know for a fact that this would enhance a room that requires sound transparency if use as cladding for a music room, sound room, etc.