....................carter AFB 4120 is a weirdo, it doesn't have the regular Carter AVS/Eddy bolt pattern so I cant just go get a phenolic spacer off the shelf, .....................
Of course it's standard!!!! The older AFBs just had the 'narrow' bolt pattern, most common Holleys had the 'wide' pattern, and many adapters/ spacers have BOTH bolt patterns, like the one below:
This one is a little expensive, but if you Google some, you'll find a cheaper one