Mustang Drift (I need help with suspension coil-over setup)

I got a 2002 Mustang GT 5 speed manual, i got it used

it already has some suspension mods on it
BBK Specific Rate Lowering Springs ( Lowers 1.5" front and 1.5" rear ), and some after market struts/shocks
Im very surprised that the car does not have a bump steer kit on it considering it was lowered so i will need to get an adjustable bump-steer kit

there are some Maximum Motorsports Caster/Camber Plates (i'm very glad the car came with these)

Alright down to the main point i want to switch over to a coil over set up and i did find some mustang 12 inch front and 10 inch rear adjustable coil overs for a good price 450$ (Front and rear coil over kit uses existing shocks and struts) but the problem is i need to know the proper spring rates i should get for a 3,280 lbs curb weight car.
Here are my Front Spring Rate Options: 12-130, 12-150, 12-170
Here are my Rear Spring Rate Options: 10-125, 10-150, 10-175


heres a link to the page of the coil overs ive found
http://www.uprproducts.com/mustang-b...r-package.html

i will be getting some Maximum Motorsports Full Length Sub-frame-Connectors, and i will build my own strut tower braces and a roll cage while im in Motor Sports chassis fabrication at wyotech (HUGE SAVINGS plus im not paying someone to do it for me)