Holley 1945 carb direct replacement for a slant six? Ideas?

Either he's made a mistake about the Autolite one barrel having a different bolt pattern than the slant six, or they've used a different flange pattern than probably 90% of the Autolite one barrels made, because that swap is something I've done first hand. I used an Autolite one barrel on a slant 6 in a forklift years ago and it bolted smack dab on and worked fine.