Just a couple of examples of how an engine will still run when something is not right. If you know something is off during a build why not correct it? Especially when it's relatively cheap and easy to do. If you look at the pic the OP posted the contact point of the roller is off to the side of the valve tip and it looks like the rocker arm is contacting the retainer - the shaft needs to move.
Aeroflow SBM heads - China castings, I think it's just a speedmaster head they put a different valve job on and put in their own box.