If your intake has a 4 bolt pattern it is for the small base Rochester 2 G carbs. To do it right it will cost you a few bucks because even if you score 3 good used carbs you need to do some modifications to make them work right.
The end carbs are just dumpers with no idle circuits so you need to either block those with some solder or similar, or buy two special bases from someone like Speedway or Vintage Speed. I am doing the same thing on my 394 Olds using some Rochester carbs with side inlets I scored on Ebay years ago. They were basically used on things like mid 60's 283 Chevy engines and cars like that.
I bought the two base kits from Speedway and also 3 rebuild kits from NAPA, but I have decided instead to send the carbs to All American Carburetor here in Florida and have them totally rebuild and dye the carbs. It will cost me $220 per carb, but my Son had that done on the 455 tripower setup he had on his rpu, and they came back looking like new, They do things we don't normally do in a rebuild, like rebushing the throttle shafts and stuff like that. The carbs are run in on a test stand to make sure they flow right and are jetted correctly before they ship them back to you.
Then there is the matter of progressive linkage, and again, I went with a setup from Speedway.
You can get by cheaper by buying the NAPA kits ( I think I paid $ 15 each) and soaking and rebuilding them yourself, but you will still have to modify the bases on the end carbs or buy the special bases I mentioned earlier.
Don
