Oh Wow, thank you so much for these Andrew. So on the drawings, the angle next to the DT is from the ground to DT? Therefore, the ST/DT angle would be 180 - 74 - that number? So, on the 700C frame, it'd be 180-74-51.3 = 54.7*, which is even worse than I thought (at 56*).

I was thinking of fillet brazing the BB, and lugging the rest (because I like lugs...).

Unterhausen pointed me to the free version of BikeCAD online. I'm going to play with a few more options there, but thank you so much for these drawings and the offer, Andrew.