I'm going to get my promag working and I'll post when finished. I'm going to build up the mag top and file and sand until it's just right. Let you know how it works out. I just don't like the angled look of the black dog, and the internals on the promag look great.
If you haven't used them, the promag 32rd banana mag is one of the best running, steel lip mags I own (and I own all that I sell). It took a few mags to break in but now runs fast or slow. Has been tested in 3 other 10/22 of varying vintages with identical results.