mechanical 3.6 sensor Q's
 

I'm getting set to install a 3.6 rear end into my NA6 chassis and I got a 3.6 sensor (electronic) with it, without doing any research thinking it could be adapted. oops.

Did some noodling on the internet and found the part numbers for the build-your-own speed sensor. (For reference, my shopping list is as follows)

1011-17-442A (aluminum sleeve)
9922-20-214 (roll pin)
9958-60-8166 (internal oil seal)
1011-17-443 (sleeve oring)

However, I'm not sure which gear I should get. Tire setup is 205-50-15, trans is 6 speed.
M502-17-441 is 19 tooth
M503-17-441 is 20 tooth
I want my speedometer to be as accurate as possible between those two.

PS- anybody need an electronic 3.6 speed sensor?