Ray, I've been working on this same tutorial and hopefully with this thread I'll be able to see the light. The next tutorial in that same book has me pulling hair out as well when it comes to that diagonal dimension and assigning LenA1 to it. It just won't take that label..
Could you possibly summarize the areas of the generic 150 psi slip on flange where your troubles were? I think I'm having the exact same problems.