Engine now smoking after new valve seals

Hey all. I have a brand new 440, has 15 minute break in and 5 miles drive time. I popped the valve covers and saw some valve seals were getting shredded. Otherwise, car was running and driving phenomenal.

So popped the heads off, to the machine shop, they cut the valve stem seats down and installed new seals.

Get the car back together, and it’s smoking like crazy out of the exhaust. I rechecked valve lash, looked at the valve seals best I could through the springs….all looked ok.

I’m assuming poor valve seal job? What else could not be when the engine was running great before?

440 Howard’s roller cam, lifters, springs and 440 source roller rockers adjustable. Iron 452 heads with stock valves.