Ignition help - no spark

Hello all. I recently purchased a 74 Duster slant 6 that hasn't been started in 14 years. I replaced all ignition components (except ignition switch and starter) and still have no spark. engine cranks kind of slow as well. I did have a little spark last week and it seemed like it might start, but now nothing. Will dist. p/u not gapped properly cause no spark?
I am at a loss at this point, so any suggestions would be greatly appreciated. Thanks!