[Zeke's Garage]

A bouncy needle is going to be caused by the flex in the speedo cable shaft. You need to remove it completely (kind of a pain to get the hold down off below the master cylinder/booster), take out the flexi-shaft and clean the snot out of both pieces with your choice of liver damaging solvents. (Engine starting fluid is my favorite). Once you get all the old lube out of the cable housing and off the flexi-shaft, use a lube specifically for cables, or a graphite based lube so that it won't get gummed up again in the future.

As for the speedo off-set, you need to figure out your tire size, rear-end ratio and transmission type, then use one of the calculators found on the inter-webz and determine the color of the speedo gear drive you need.

Good Luck!