Alternative Rear Seats

Hello!

I'm in the process of fitting 4Motion bora seats into my mk1. Only got a couple of things to assess before they will be in comfortably.

The front seats are in and working perfectly, and the rear bench is pinned just as it does in all of the 2000 series VWs (bora, golf, lupo etc)

The bit im still pondering is the rear upright/backrest. Has anyone managed to fit later VW/Audi seats into the rear of their mk1? and how have they gone about supporting them and bolting them in?

Im not too fussed about them easily folding forward or anything, since the boot will have a build in to support the air ride. And just for the record, mine is a 5 door.

Any input is appreciated!

Cheers, Dan!