Well the JH motor off the older 83-84 GTI, Cabriolet, and Scirocco 8v has an 8:5:1 compression. So its probably much easier to turbo b/c of that. The 16v has I think a 10:1:1 compression or something like that. The MKII 8v's had higher than the GTI, Cabriolet and Scirocco.
There is a Callaway Trubo Scirocco for sale on TVD. I believe its 8v turbo. You can also do 2l aba turbo.