Well, i must confess to not being a gearbox expert as to speak, thats more of my business partners area (mark, but he's away for xmas), i'm just going off what ive had experiance with and some of our customers cars.
Mark used the diesel 02a box on his 1.8t converted mk3 and the tall gearing was spot on, because with the 6 speed boxes you end up reving out too quickly and hitting the limiter before you get a chance to grab the next gear. Also the diesel gearset is supposed to be stronger to cope with the diesel torque.
As i mentioned earlier, a customer of ours had used this same setup (as recommended by Mark) for just over a season (which was half a season longer than his old quafe box lasted!!), before it gave up, so he's trying again but has had them cryogenically treated to see if they'll last 2 seasons!!!
If your happy with the ratios in your 02j, then its got to be worth a shot at getting them treated.