Mark Donnelly did some really nice pistol work--his trigger jobs were very impressive.
He went out on his own, and set up a shop in Hudson.
https://www.consolidatedfirearmservices.com/
He doesn't work cheap, but he certainly knows his business.
He'd be worth a call, but if you want ten minute turn-around on night sights, you'd probably be better off with Four Seasons. Didn't they used to have an "installed while you wait" deal on Friday or some such, if you bought the sights from them.
That being said, if you want to turn your POS Shield with a ten-pound trigger pull into a no-sh*t carry gun, Mark would be my go-to. Night and day difference.