and a wiring harness
http://www.nelsonperformance.com/?page_id=850
All I really find are wiring harness for a 1998 and newer 4l60e to 4l80e conversion (ebay has a bunch too), but not my 4l60 to a 4l80e.
do such harnesses exist?
Just to clarify, that harness would work for you if you had a 4L60E. 60Es and 80Es all use the same plug for the most part. I actually used that harness in my '97 60E to 80E swap, along with their pinned input speed sensor harness. But from what I'm gathering here you have a 700R4, which is basically the same transmission but I don't believe they have a wiring harness at all. (Hence the TB cable) I could be mistaken as I've never been up close and personal with one. (EDIT - Looks like they do have some, but it's very minimal and just controls lockup.) Pretty sure that's why L31Max said you'd have to add all the wiring for the transmission and a VSSB.