Ok brief into.. My brother has had a knee injury and cannot drive manuals now as comfortably as before

I was wondering whether the 1800 auto gearbox from the driver can be fitted to the 8v gti engine? because these engines and gearboxes are all very similiar. Does anyone know whether this is possible im willing to give it try based to how much positive information i gather.
I say this because its currently a 1600 driver with weber carb and gti cam. And i used to mess around with my 8v gti and the engines n gearboxes all look very much the same, and most VW parts are interchangable anyway.