I have an essentially new square bore Holley 850 CFM carburetor model # 4781, with mechanical choke for sale. I ran it one time for about 10 miles and decided to go back to a Rochester carb. This carb sells new from Summit Racing for $485. $300; buyer pays shipping. http://www.summitracing.com/parts/HLY-0-4781C/ Please call if interested. Phil 303.587.3054