Alluminum trailing arms in a splitty

[pondoras box]

Doeas any one know how to install Porsche trailing arms into a split window bus that has been converted to an IRS setup. The trailing arms have a cast in ridge that will not allow the springplates to fit flush. I dont think that I can use Porsche trailing arms due the fact that I need to use modified bus items. But if I try to clerance the springplates that came in the kit there is not alot of metal left between the bolt holes. Any suggestions? Pics of a conversion would be great. I would like to use the Porsche items if I can, not type one parts.