Another carb question

It looks like it has two patterns, one for the Holley 350/500 2bbl., and if the smaller pattern is too large for your BBD (I'm assuming it's a 318 BBD), my guess is that it's for a Holley 2210/2245 (360s and 400s)or a big block BBD (383s), which used a slightly larger bolt pattern. I think early 60s 383s used Strombergs, which personally I would steer clear of...