prepping 924S for spec 944

im taking a 1987 924S and turnig it into a spec 944 racer. so far ive got all the mods that are allowed in the motor with the exception of the shaved head. the rear seats and carpet are gone and the car sits at about 2700 lbs. problem is, i dont have a roll cage and cant find one for under $700. i met some guys out at willow springs a couple weeks ago and they had some konis and some coilover sleeves to sell me but i havent herd from them since so i pretty much need a whole suspension setup *the car is stock with boge shocks and M471 spec parts*. More or less my questions are what would be the least expensive way to get the most out of my car as it sits and get me within reach of the fully prepped cars? I know a large part of it is the driver and im willing to practice, but i also know that with 220,000 mile springs, shocks and torsion bars no matter who the driver is im never going to pull a 1:40 or less lap at willow springs. if anyone is in southern california and has used parts to sell or knows where to get new ones for a good price please contact me at zanghiracing@hotmail.com. thank you.