With only 122k your tranny isn't going to die for a while bro. My brother has treated his 96 Auto RS like pure shit from day one, now has 215k on the same motor and tranny. So if you take any kind of care of your car, most likely that tranny is still in good shape.

Now, IMO, from personal experience...I once rode in an Auto LS w/an intake, header and exhaust and to say the least, when he bumped it from one through 4 it seemed to move pretty good, you could feel the slight delay in the shifting, but it seemed to be moving pretty quick. On the freeway when he would punch it to pass it moved pretty good too. Sometimes he would shift back into 3rd and that seemed to get the car going too.

So there is hope if your ok with that kind of performance.