The ones you want came on cars like early to mid '60's 283 Chevies. There are two versions, large base and small base, you want the small base, and those were used on cars like I mentioned.
The side inlet makes it easier to run your fuel lines as they are out of the way of the next carb. You can either buy a NAPA kit, soak the carbs overnight, and rebuild your own, or send them to one of the carb services to have them redyed and all. They come back like brand new.
I think they flow about 170 each, so one would run a 305 just fine, but it wouldn't take much more work to make them all operational. Gastrick just went through this on his '32 and may be able to give first hand info on what he ran in to.
I have 6 of these carbs, 3 for my '39 Dodge and 3 for my T someday. I bought them all off of ebay and paid about $ 15-$ 25 each. I won one as a whole setup, 2 barrel intake and carb. I told the guy to put the intake back on ebay, all I wanted was the carb and didn't want to pay to ship a heavy intake I didn't need.
My Son Dan sent his carbs off to All American Carburation and had them redone. He has an original Olds 442 W30 setup, and they charged about $450 for rebuilding and replating all 3 carbs. Did a fantastic job. Here are the before and after pictures.
These are the real McCoys as far as tripower carbs go. You will notice the end carbs are shorter and have no idle adjustment screws. That is how you tell the difference.
Don