My home inspection of Speedmaster heads
I'm a knurling hater.
Cheap way to tighten up a valve stem and the best way to build up carbon on the inside of the intake valve.
I would run a loose, new, bronze valve guide all day lone over knurling it! lets just give the guide a oil groove for the oil to run down and drip on that hot intake valve.
If my grannys 318 Cordoba, that she drive 300 mile a year in, need a head rebuild, i would consider Knurling.