I'm not quite sure what you mean by op-up a J fare class even though it's an award ticket...unless I'm reading you post wrong. A J fare in and of itself is the top of the business fare bucket..

Business class fares go J, C, D, etc....Op-Ups will happen by members status (GS,1K etc) and fare class...i.e. A GS with a J ticket ( that has been paid for with $$$ and NOT an award) will be first in line for an op-up...unless I'm mistaken.