id put a vr in it its actually not hard, and u will get the most bang for the buck,
the easiest way is to make sure you get a late model block that has mk4 mounting holes in it get some stock mk4 mounts and drop it in and make a dogbone mount,
or make up some mounts like that, some 16v axles and you are golden,
and trust me it wont handle as bad as everybody says just get some good suspension and u will be fine i loved my vr6 rabbit and im in the process of collecting parts for a vr rocco myself,
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EuroRat #2+#3
"YEA THOUGH I ROLL THROUGH THE VALLEY OF THE SHADOW OF RICE, I WILL FEAR NO TURBO FOR DISPLACEMENT AND TORQUE ART WITH ME... MY RODS AND MY PISTONS THEY COMFORT ME.."
bought not broken!!!
member #2 
"having a big turbo is like having a big dick; it's not immediately obvious to everyone, but you have to just rest assured that when it comes time to put it to use, you won't need to explain a whole lot afterwards"