What is the ratio of the speedo that you have (i.e. 2:1, 1:1, etc.) - that will make a difference in what drive gear would work.
do you have a spacer between the left side of your wheel hub and the slider? If not you may have to go to a wide glide trees to bet space for the speedo drive - or maybe a different wheel (hub)
I think there is a page in the catelogue which lists many (most) of the front wheel drives available, with the specs for each - check it out
When workin' on your ride the first tool out of the box should be the manual