A Rallye or G60 Passat Syncro gearbox is a direct swap, however you will need to change a few more parts over as well as the box, things like the Flywheel & clutch assembly, gearlever mechanism, drive shafts, clutch operating system etc.
btw you do not need to change the rear axle as it is compatable with the Passat gearbox/transfer box
Dan (housey) has just done this conversion so he should be able to state what extra Passat parts he needed.
The rod change box won’t hold up to 170 bhp for very long, especially when “thrashed”
you will very shortly be able to say “thrashed to death”
Here is whats on ebay.de at the moment. http://shop.ebay.de/?_from=R40&_trksid=p3907.m38.l1313&_nkw=G60+syncro+getriebe&_sacat=See-All-Categories