Think I answered you on one of the FB groups... look for Carter YF 2101S for the '54. The 966S was spec'ed as a replacement for the 235 through '52. Probably work, but the newer spec carb should be a better match. They pop up on eBay from time to time - there are 3 or 4 cores listed now - but nothing that looks great at the moment.
You might want to post to the Swap Meet "Parts Wanted" forum.