the tranny will fit but it wont be up to much, the pump wont, M-TDI isnt just an IDI pump on a TDI. you eather need to convert ur pump which i wudnt recomend or buy a cable operated TDI pump and make it fit. you cud just run the ecu and fly by wire off the jetta, might be easyest way, tbh id run the jetta gear box if you can get drive shafts that fit
the tranny will take about 140bhp at a guess, i was running the same in my aaz and it fell apart at about 200. ull have to run the backwards set up. over here its realy easy to get a cable TDI pump, can pick one up for about £30+ and then sell the stock pump for about £80+ dont know why everyone doesnt botherthere are lots of different pumps that will fit, not just VW