Dick,
You have described just what you need to use a "guide board" which in a smaller version would be a "taper jug"
Basically start with a piece of 3/4 hardwood plywood that is about 6-8 inches wide ( for stability) rip it clean on both edges with the table saw. Determine how you would like to affix a couple of "hold down" clamps or mechanisms. The easiest thing to use are the toggle clamps that you screw down to the surface. In other words, you want to be able to hold the pieces of wood at an angle to the blade ( 2.25" at one end and 2"at the other) The clamps should be about 3" to the right of the cut line so they bear down on the wood that you are cutting. You did not say what the width of your unfinished stock is so the clamps and the "sled" need to account for the average width of the wood before you taper it.
I am not sure if you are a beginner or not, but many of the magazine sites show a sled such as this for ripping a clean edge on raw rough sawn lumber but the same principal applies. Write back to me directly if you have any detailed questions. I will be glad to help you.
Regards,