Your air box is correct the RB air box only has one air intake. A second smaller intake was added to the left of the original one on the RC/RD models. This is part of the reason why the RB is quoted at 115 HP and the RC/RD at 120 HP. Best not tell RC/RD owner though.
I also believe I am correct in saying the R air box is different from the 900/750. If my memory is correct Andre had fuelling problems when he had a bike fitted with the wrong air box. I’m sure he will let us know.