The only way you can do this with the Bilstein's is to look on the forums for a good used set of Coilovers front and rear. Otherwise, the Koni's would be the more economical route. I am not going to bring up the Koni vs. Bilstein issue as it has been beat to death here. Keep in mind if you delete the torsions, that's extra work/cost on your part.

If it were me, and I was doing it again. I would hang on to the $1400... Buy the KW Variant's for the 944, install w/ torsion bars and be done.

 

Actually, I think it is.

I have 440#/in up front, rear is 175#/in coilover + stock t-bar, per the recommendation of Ground Control. They made that recommendation based on (extensive?) testing, not just theoretical calculations. It's always worked very well for me. Setup includes a 26.8mm sway bar up front, 19mm 5-way adjustable sway bar in the rear. I can adjust the rear sway bar to make it loose or just barely tight, so I'm almost perfectly balanced. I could probably increase the front sway bar diameter and gain a little more balance.

At the spring rate you have, you should be able to completely remove your T-bars without changing the coilover springs. Your 350# springs have a higher effective rate on the rears because the mounting point on the trailing arm is forward of the wheel.