Sounds like all you need is to gear up a bit. A 22 pinion is very short gearing for a stock motor with a 96 spur. I'd go up to a 30 and maybe a bit more depending on the motor.
There's no reason a good 27 turn stocker can't keep up with or beat the brushless motors... it's more work with the maintenance involved, but definitely doable.
There's also no reason your 12l can't still compete. Does your car have the symmetrical t-bar, or the older non-symmetrical one? If it's the older type, that might be the only issue... I'm not sure you can even get the older style t-bars anymore, and they do wear out after several race days.
I'm assuming you race at Madness in Enfield? IF not, please let me know where you race... I might be in need of a place to go soon...