What he said. If you pull the OSB and put the 1 1/4 hardwood right on the framing it should put you where you need to be. you could put cleats and reset the OSB between the framing flush with the top.
Kevin
I was thinking about the cleats and inset plywood panels but thought it would be kinda uneven in surface if the plywood would be lower or higher by a 1/16 here or there to the top of the joists.But now that I think about it, that can be fixed by using a belt sander to get all the tops relative flush. I just hope that if you went with this plan that the current plywood top was screwed down and construction adhesive wasn't used because the construction adhesive would be a real pain to remove off the joists.