My dad was having trouble with standard 2bbl on his '63 Impala 283. Someone gave me an Edelbrock 1406 4bbl so I put it on with one of these kits because he doesn't care about HP, he just needed something manageable and didn't want to waste 200 and lose supplies. So I put it on and it had a massive vacuum leak after I took it off. I noticed that the corners of the 2 cylinder side were open, the gasket holes were too big so I had to cut a special gasket to fit, then I noticed there was still a big leak, there are 3 sets of holes for the 4 Bbl side and a hole is open for the vacuum passage on the passenger side so I found a hex bolt that fit very snugly, welded JB weld on it, rammed and trimmed it flush. now it works and works well, but it's too much work for a purpose-built part. Don't waste your time with this design if you use Edelbrock