Have you rechecked the plugs since the 4 of 8 started to misfire? I would start with simple things like making sure all plugs are getting fire from the distributor. Did you adjust the carb after reinstall? Have your checked timing? Did anything happen the last time it was running right (backfire, misfiring, got gas at an unusual location ETC)? Just a few ideas to get you started, hopefully someone more knowledgable will jump in and help you out some. Good luck and Happy New Year
