Whilst I know nothing of what's available in the States, I'm sure there are plenty of engravers around, doing company wall plates, control panels, etc. Used to use pantograph engraving machines, but now use computerised things. Anyway, they always have offcuts of engraving quality brass which they'll sell you by weight. I always buy my CZ120 that way.
Also called silicon brass, leaded brass, half hard, etc. Free cutting and a lovely light colour. I have made nearly 500 brass patterns for the model kit industry from this stuff, all polished and all looking sweeter than gold when newly finished.
Old clocks though,....well I heard the plates were once made from what I call "yellow brass". I hate the stuff, but if that's period correct, I understand that there are suppliers of that in Birmingham. Not sure about the States, though.