Another speedo drive question

[olddaze]

Built a Frankenstein transmission for my Shovelhead Trike project. Basically it's a `69 e-start case with a hand shift lid on it. I had planned on using the factory speedo drive that is on the Servi-car axle to drive my speedometer, so I didn't pay much attention to the drive in the transmission because I didn't plan on using it. Forgot about the fact that I am running the axle flipped upside down to drive off the left side (Oops). Axle drive now turns backwards.
So, I need to fall back on the transmission gear to drive the speedo. Peeking down through the drive hole I count 5 teeth on the gear. Which drop-in drive unit do I need? 11, 13, or 23 tooth? And what ratio speedometer will I need to scrounge up?

[bmh]

Are you sure you got 5? I thought the options were 4, 7, or 8. with two different 7 tooth gears.

[olddaze]

Sure looks like 5. But the trans is in the frame so it's hard to get a real good look at it. If those are my options, let's call it 4.
What drop-in do I need? Resulting in what ratio speedometer?

[bmh]

According to the chart Perry posted in another thread that would be a 13 tooth unit with a black gear. I think that's a 1:1 ratio speedo.