Stock heads vs Big valve etc heads.

Dumb question, do he aftermarket ported heads like Steig and Coy Miller etc use the same valve seals? Larger valves are the shafts and guides the same?
If they are all the same where are you guys buying the seals and what brand should I be using?

My CMRE stage II heads are using stock-sized valve seals. I'm running Auto Zone seals currently