I have been a fan of the Rochester fi for 50 years got my first one in 1962 traded a 4 barrel Rochester carb an d cast iron manifold for it. I made it work really good but it was made to support 283 hp on a 283 cu. in motor and it has a tough time doing that as a mater of fact a properly tuned 4 barrell carb will carb will out perform them I have owned probably 20 different units over the years I only have about 3 late model flat top units left the flat top started in 63 thru 65 365 and 375 hp. I even owned 1958 Pontiac unit that I wish I still had I have a polished and chrome one on my 32 and have run them for years but as for performance is concerned your better off with a 4 barrel there are a lot of people a lot smarter than me that over the years have tried to make them perform the problem they are a cheap thin di cast part you can't port them to get enough air in. That said they are sure neat units and fun to run every place you go you will find young guys that have never seen one befor. But don't waste your money building a 383 because it will just run like a 283 so build a power pack 283 with a solid lifter roller cam and have fun so that's my 2¢ worth ......ted