More Teeth on the Speedo Gear Will Make Speedometer Read Lower, Right?

It has been a long time since I thought about this. I have had 205/70/14 tires on all four corners of my 69 Cuda with an 833 4 speed for a long time. The speedometer has been off by about 10 MPH for a long time. If the speedometer reads 65, I am really going about 55. I am finally going to do something about it. It seems to me that if I take the speedo gear out of the tranny and count the teeth, that my speedometer will read lower (more accurately) if I put in a new gear with more teeth. Kind of like a ring and pinion gear ratio question, right? With the ring gear being the speedo gear that I remove.