Finished the bracket this a.m. and hung it up for paint. It fits perfectly and has the stiffness it needs to do what it's supposed to. 
Can I just say that having a bucket of scrap steel and a little wire feed welder has changed my life immensely for the better? Just a few years ago—like when I was putting the Suby in Bridget—I could not do half of the things I do these days as a matter of routine before breakfast.
@ALB right: one more hole. I'd left it out because I wasn't yet sure how/where the reinforcement bit was going to fit.