I agree that it appears that the typical assembly (O.E.M. 1958 - 1960 T-bird w/430 MEL) consisted of the Carter product, but interestingly Ford & Holley have a listing for the Holley (model 1860) carburetor also (Ford #5752426 stamped on the air horn, tag code #CKM9BA, Holley #R-1850AAS which may appear stamped on the carburetor air horn as LIST-1850). These units due exist, and are present frequently on Ebay, relatively to down-rite cheap asking prices (no takers, no application T-bird anyway?).
Maybe, some earlier (1958) production T-Birds? Scott.