OK, I have had to bike to the local 1/8 mile. It is clear that the gearing is too tall for this distance. My first thought was to change to an 883 front sprocket, which traditionally was two teeth smaller than a 1200 (27 and 29). However, the 04-05 883 sprockets are actually 28 instead of the old 27 tooth on pre-04s. The 1200s are still 29 tooth, but the part numbers for the new 29 tooth ones are different from the pre-04 29 sprockets, so my dealer doesn't think the older sprockets will work. First, has anyone tried a pre-04 sprocket on a newer Sportster, and if it doesn't work, will one tooth lower make a difference in the 1/8 mile worth the expense? Obviously, a bike that will do 80 in 2nd gear is geared too low for the 1/8 mile. Any other suggestions to get this thing geared down?

Shooter

.... will one tooth lower make a difference in the 1/8 mile worth the expense?

NO. The difference at two teeth is barely worth the price of a new front pulley.

If you gear the bike for 1/8 mile, the top speed, when at redline in 5th gear will be maybe 90 MPH. 1/8 mile gearing is radical.

Conversion to a chain drive is the best bet.