Jetting is different between the big block and small block carbs however jetting is easy to change.
The problem with some 1.08 carbs (C6SF, C6AF just to name a few of the 1.08's) that were designed as smogger carbs for the big block engines. The big engine carbs use different booster venturiis than the small engine (289 cu.in) carbs. This was done to still have some running quality and performance with a small carb on a big engine and still meet emission standards. The truth is performance still sucked. Those smogger carbs are very hard to tune, you will not be happy. The only way I have found to make them work to my liking is to swap the booster venturiis from a small block designed carb. If you have to do this you may as well purchase the "good" carb the first time. That is why if you see a Mustang carb listed (C5ZF, C6ZF) the seller is asking an additional $200.00 plus for that carb vs a C6AF or C6SF 1.08 carb. Those Mustang/289 engined carbs are so much better engineered.
Another thing is if you are using an Autolite 4100 on the "B" manifold you have to use a spacer under the carb or you will have a vacuum leak at the front of the carb by the idle adjuster screws. The 4100's have a bridged mounting base instead of a flat mounting base like the Holleys or Edelbrock's also the base is slightly larger than a holley. With the bridged base the contact area between the carb base and manifold is near zero at the front of the carb. After a couple of weeks the gasket will be sucked out.
Yblocks like spacers under the carb so works well to use one. I usually use a 1" spacer others have used 2" with good results. You hood clearance is the issue with some engines.
Try this fellow. I have heard very good reports on his work. He is a regular on ebay also. Again I have no interest in this company.
KP CARBS
103 CRISFIELD CIRCLE
MINOA, NY 13116
PH# 315-263-5979
E-MAIL: CARBONTOOTERS1@HOTMAIL.COM
marv