Hi Todd, and welcome to ITS. Ive built 2 944 ITS cars both with custom cages. I used the Jon Milledge Engineering diagram as a guide. Couple things to note, yes place the main hoop on the shelf as you mentioned, run the front through the dash (the tubes will be where your heat/ac vents are now). For the rear go down to the edge of the shelf of the trunk, you're trying to hit where the rear shock mounts, look under the car and you will see where I mean. Do drivers side nascar bars, its very tight in my new car I went with an X this time (i will be changing this). Petty bar from the middle section going to the lower part of forward down section, from the front down I also made it an 8 point by extending to front pan (again trying to tie in suspension. Chris Howard from here in Massachusetts did my cage, I think he's in Hopkinton MA, if you're in the area call him you'll be very happy. Russ