First I would do is verify TDC. Its pretty common for balancer rings to slip on the rubber ring, so the timing mark isn't always a good indicator. Don't worry about being a tooth off... that is only a problem with points ignition. With more modern ignitions, it doesn't matter what tooth its on you just turn the dizzy until its lined up right.
Second I would verify the carb tune. Look down the throats while its idling. Is there liquid fuel dripping from the boosters? If there is, chances are its a blown power valve or a needle/float issue.
This is assuming that you have the firing order right. I know, its a stupid thing for me to say, but I have chased all kinds of issues only to find out that I skipped the basics.
Help us out.... cam specs and compression?