Rear suspension setup / options ?'s

[muddstir]

So I'm getting close to starting my first 2wd build and I got some questions.

So my plan with this truck is to make it a driver but go to the track with my friends (drag strip and maybe a road course) but just to have fun. I also want to still be able to haul toys in the bed and pull a trailer down the interstate.

Truck specs- 71 short bed, 6.0l with a 6speed manual. I want to install an upgraded braking system with disc brakes on the rear but not sure what system yet. Rear end is a 12 bolt. Don't know what I want to do to the front system but 2.5in drop spindles will be installed.

The rear setup has a new trailing arm crossmember (I think it's the cheap eBay special one) but looks decent, and that's it. I did just order the cpp totally tubular trailing arms.

Now my question is- what is my best option for springs and how low can I go till I have to c-notch the frame (I don't want to c-notch / but I feel like it like to drop the ride height down 4in ).
Drop springs, air bags, or coil overs not sure what will work the best and work with what I already got. And is there anything else that I need for any of them to work with what I got. Like special crossmember for shocks or brackets for coil overs ect.

Sorry for the jumpyness of this post.