I once owned a Springfield M1862 Rifle Musket. When I got it, it had been used as a toy for over fifty years. I sprung the rammer to find at least two loads in the breech. I called around and found a smith competent to work on it. He unbreeched it to find........Wait for it........two full loads in the breech. He saved them for me, cleaned the bore, cleaned and oiled the lock, and installed a new nipple. Other than a gentle wipe on the outside, that was all the cleaning needed. I borrowed a Lyman .58 Minie Ball mold and cast a few hundred pure lead minies, and shot it regularly for several years until I was offered so much money for it I couldn't say no. I still regret selling it, but being a young father with a wife and two kids overrode keeping the musket.
I'd say get it checked out by a competent smith and if found in good order, by all means, shoot it. I would not do any more restoration than necessary to put it in good working order. A new nipple, dismount, clean and oil the lockworks and wipe down the stock and barrel with an oily rag is all I'd do.
That kind of maintainance will preserve the value while allowing you to shoot and enjoy your musket. Of course I'd replace any broken parts while keeping the originals tucked safely away.
Those loads that were in the breech? That powder was in as good condition as the day(s?) it was first loaded. The smith fired one and I fired the other.
Three Hawks