Moved your thread from Site News to Engine Performance to get you some help here.
Sounds like something is 180 degrees out. But, go ahead and time it off the #6 and see it runs. If it's good, does it really matter where the light times from? Most of us actually time by ear since timing chain wear, distributor wear and such in these old engines can affect the light making it lie to you like a $10 crack *****. There's still reasons to use a timing light. I verified a bad harmonic balancer by using a light for example. If you're not real good at timing by ear, it'll at lest give you a base to start from. I prefer using a degreed timing light and I can verify timing by marks as called by the book. Then advance or time by ear and performance from there, lock it down where I like it, then use the light again to find out where my happy place is and record that. Next time I check my timing I can put it right back in the same place and if performace isn't as good then I know I have even more timing chain wear and will compensate even further. That's just me though. I'm certain others will disagree or have a different technique how they do their.