the 98 is much better than the 700r4 with the Gen3 swap. It will simplify the swap by leaps and bounds since you'll be able to plug the PCM transmission and speed sensor into the 60e. A 1999+ V8 60e will allow you to get away from the adapter but the one you have located will be no issue. Be sure to test fit the converter to your flexplate before putting the trans in, you might have to elongate the holes in the plate a little to get them to line up.