You need 85' or earlier rears for a "bolt on" steel trailing arms will work, but not the ali ones (as you have found out) Have you looked at Lanner's site? Here is a link to the tech page.
http://www.vdubengineering.com/techn...onversions.htm look at the products section to see T2 conversion options He has, but He can do pretty much any kind of brake conversion.
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1970 T1 W/MassIVe 2913cc RAT/?EFI? w/direct fire (very soon) and 915 trans
1962 SC 1776cc SP 944NA brakes, 993 wheels
VKG