It's not unheard of to end up with tight guides on rebuilt heads. Some machinists are too _____ lazy and never check this stuff. Same with cleaning oil passages etc. They'll charge you for it, but did they really do it?

My brother ported a set of Pro Comp(?) heads for a small block Mopar a few months back and several of the guides were so tight there was no way the oil would ever be able to get in there and do it's job. People get angry when they find out their new parts need work, but it is what it is.