Great news, I've been following this thread. I'm sure you were second guessing everything you had done when building this. I've been there myself (I can imagine that most everyone has at some point as well.)
The 1st time I had the same exact problem you had, quite a long time ago, I ended up using a timing light while cranking. I had the same issue, off by one cylinder on distributor installation. Since then, I use a timing light on initial startup. It definitely eliminates all of the guessing of what exactly is happenning.
Good luck with your project!