I'll post some pics tonight. But I channeled the subframe (when I say I, I mean Kev Rowley and I. When I lived in Brisbane. I planned it and we executed it...consider him a good mate of mine) and reinforced with a fair bit of steel.
I used the S13 platform, s14 LSD, 300zx hubs and brakes and 300zx turbo axles with s14 driveshaft 'hubs' (or whatever they are called). I also created (by my own hand) some strut turrets in the tray using the s13 tops, which fortunately match the 300zx struts. No matter how hard I tried I could not reconcile rear suspension to the chassis, either direct or using an inboard system...for the travel I wanted, which was approx. 130-140mm from memory. I have all of the chassis diagrams matched up if that would help.
I strongly recommend getting the diagrams from the IRS you are using and referrencing everything to the common "ground" measurement.
It turned into quite a problem solving exercise. To be honest, hindsight says it isn't worth the trouble...but I loved the engineering exercise.
I'll PM you when I find the photos
Michael