I am thinking about building a 9mm AR Pistol. I have a stripped PSA lower laying around. If I purchased a Colt 9mm SMG Parts Kit (minus the auto sear) will this kit get me started https://whatacountry.com/colt-9mm-smg-parts-kit.aspx ? I would install a PSB and not the adjustable stock and get the drop in magwell adapter. Thanks

Any particular reason you want to spend that much money on used parts?
You can build something just as quality for a fair amount less.