What should i change to get into high 11's?
Steeper gears and a better converter could get you into the low 12's, but that still leaves you a second a way from your goal...you will have to add a LOT of power to get there (about 100 hp)....but it really is a good COMBINATION of parts that work well together that is key.
I would start with the 90/10 drag shocks in the front and frame connectors.
I would not get the gears or the converter until you determine what you are doing for the additional power. Compression, cam, intake, carb, converter, gears, etc, should all match to make the most of what you've got. As you said in your first post, you want to do this right the first time...so take some time and plan it rather than buying random parts. JMO.