Did you align the frame using a surface plate? Even small amounts of misalignment take a significant amount of deflection tweaking to bring them into plane. Typically if the frame can live though this ordeal it will be fine on the road.

Regarding other ways to check the frame I always watch inside the BB for brazing material to come though after feeding it in from the outside. Once you get a feel for how much to feed and how far to pull it down, your confidence will go up with the build.