Ok....I think this is my solution unless I can find a 4150 top:

http://www.ebay.com/itm/HVH-carb-adapter...702&vxp=mtr

Most of the spacers listed 4500 manifold to 4150 carb have the holes tapped on the 4500 side and pass through holes on the 4150 side which is the opposite of what I need.

Any idea if the Wilson spacers are this way was well? If not I can call on Monday and ask. edit: Wilson does make a 4150 carb to 4500 manifold adapter...