I have about the same mods (Bscr stage 2/ walbro) but have hita 12.5 on 91 pump with a flash. I'll try to find my slips and post them to compare. I was trapping around 109 mph, so I think your if you dialed in your technique you could drop those times on 100oct if your properly tuned for it. Did you datalog your runs to see where your timing advance was?
When I drag I make use of the launch control, I never lift my foot off the gas pedal, it stays pegged at wot through shifts. I gained a couple tenths using that technique over lift to shift.
I've got gsc 272 and a stage 2 snow meth kit I've yet to install, but when I do and get it tuned and run a couple pass's I'll post up the results if your interested. From your mods and mph I would infer that our cars are probably on the same power level.
With cams and a reflash you might be able to go faster than the safc and 100 oct.