Tuning and fitting 6 speed box in a 1.9tdi octavia

Well guys don't think I posted on briskoda before but I a 2004 mk2 octavia and any problems I Google seems to through up this forum. But due to unforeseen circumstances regarding my vectra I'm possibly going to be throwing myself into the octavia again since its been sitting parked off the road for the last year. I'm planning on getting some more power from the car and would like to fit a 6 speed box . I have myself half leather l&k seats lined up and a host of other l&k luxuries (mines an ambiente ) but again I will be hopefully relying on the expertise of you guys on here to help get them fitted down the line. But first off I'm looking at hopefully getting a 6 speed fitted to my own car I have the bjb engine and would like to know what parts I need to complete the conversion as I possibly have a 6 speed box etc from 2.0 tdi to fit as from reading the 1.9 box from the mk5 golf sport is to weak I've been told. Tho I'm not looking massive power gains as i would hope to get ot up around 150 bhp plus if possible so not sure if the 1.9 tdi box would suit ??