I'm not familiar with the RB67 and those lenses but I tested lenses I have bought for my Hasselblads. I put the camera on a tripod and under a steady light condition, I took a series of exposures at the different apertures with the appropriate corresponding shutter speeds then developed the film to see that the equipment was functionally correct. I focused on the same spot not moving the camera. To be sure of your decision why not test both ways a & b.