A 360, j head with an xe268H in a Demon can run 12.50's or better in the right hands.

Takes work to fine tune the combo and with an auto, the converter is key.

I would not use a victor intake on a 340 unless it has plenty of stall. The TQ the victor leaves at lower rpm compared an Air Gap is pretty big. If you have to accelerate through that range, the victor will lag.