Markings on Stevens barrels made under Pope's supervision are no different than those made after his departure. Stevens was smart to keep the markings the same so they might continue to profit from the venture long after Harry Pope left.
Most of these rifles were based on the model 54 Stevens, and were marked Stevens-Pope on the barrel. Those barrels and guns with serial numbers under 1200 will have been made while Pope was there, if marked Stevens-Pope. Some made not long after may or may not have had his attention, but the 1200 is a sure thing. No Stevens barrels made under his supervision left without the Pope name on them, so don't fall for the hustlers who try to pass off regular Stevens barrels with serial numbers over or under 1200.