Antique Wall Tub Set Help

[Riverhills]

Looking for help on finding a suitable replacement or repair parts (stem/seat) for tub set below. In my 1923 Craftsman home. Images below. Hoping someone can point me in fight direction. Will repair wall after installation. Access from back is available as shown. Thanks.

 

[Geofd]

Not sure if that's brass or galvanized pipe if it's an IPS thread I think I would remove everything including the unions and install ball valve there and pipe in a new shower valve that spout would have to come out this all depends on your pipe condition

 

[TomFOhio]

Thats a very old faucet drain setup. If you cant find new stems maybe you can take the seats out and get replacements and new
stem washers. If you are planning on replacing that faucet that would be a large undertaking. You would be better off calling
a plumber because to replace that faucet your have to change the drain also.