I've been working quite a bit lately with something used very rarely and I'd like to get rid of some old assumptions. Level 2 Gunblaze can be flat out awesome.
lv2 GB 5S JI 5H HJC j.S, j.K, j.S JC (j.S) j.H, SV
Works on AB, AN, BA, BR, CH, DI, ED, FA*, IN, JO, KY, MI, OS, PO, RK, SL, TE, VE, ZA
In order to hit this on most of the characters, you need to take a step or two back once the GB finishes. That step or two puts them right into 5H's range. You don't really have to move with any of the heavies except for ABA, so it's quite practical to use it on the likes of Johnny and Pot. The damage is nearly identical to the level 1 GB midscreen JI.
*Unlike all of the others, Faust needs you to walk forwards and have him pass over your head. So the corner JI variant is also possible on him.
For the other characters, you can get the jump install combo in on counter hit. I've been working on it with Sol and May.
lv2 GB CH 5S(f) JI 5H HJC j.S, j.K, j.S JC (j.S) j.H, SV
5S© never seems to work correctly in this situation yet 5S(f) works perfectly.