I need a new carb base to mate to my Impco 425. I have a Holley 600 base but the throttle shaft holes are worn out. When I ran this carb on my K5 it had a problem with a sticking throttle and I could never get it tuned right, well now I see the throttle shafts are worn out and it was probably causing a vacuum leak. Anyway, all I need is a square bore base, I don't want to buy a whole carb to get a new base but I'd like to get a 650 or 750 base, vs the 600 I have. An Anyway does anyone know where I can get a kit to rebuild a holley base? Or ever done it yourself that you can give me tips? Or know of someplace that sells new or rebuilt units cheaper than this?