I'm cheap and hate to spend money, even other peoples:D. But, if you have a shop available local with a distributor machine you may want to pull it and let them run it and check for proper operation. They could also set up a timing curve for you that's suitable for your setup. As 805kid said earlier i'm sure with fairly low compression it's gonna want plenty of initial timing. Probably enough that the total would have to be limited.
From what i've seen so far i believe your carb is ok. This may be just a accumulation of a few minor things......Maybe valves not sealing 100%, timing chain has a little slack, dizzy not perfect.....ect.
Maybe you'll get a little more member input for something i'm not seeing. I'll be watching.
