Or, you could simply try to find some lowering springs/coil-overs and go from there. If you lower the car and put a big chin spoiler on the front, not much air is going to find its way under the car but you won't have to worry about big time heat buildup due to belly pans.
Springs:
http://www.eurosporttuning.ca/Mercha...Code=VL-240-su
Some people I know of have molded a newer style 850 (850 T5 to be exact) front bumper on the front of their 240s. They're much more aerodynamic and sit a bit lower as well.