The 11-28 I had in mind is
not Interactive glide. It's the "CS‑HG50‑8" cassette listed on this table:
http://www.sheldonbrown.com/k8.shtml
And about the braze-on FD, hmm... I guess a 50/34 compact could be used with the 11-28 cassette, but that would give a lot of unnecessary (at least for me) high gears. It would work great with your 13-26 cassette, and still give a 35-ish low gear.