Let's get back to basics before proceeding. Rebuilds happen for 3 general reasons
1) poor maintenance and care
2) product defect failure
3) change of use/spec
For grins sake, let's ignore the first one. For every rebuild you hear about, there is another that is going just fine after 200k, 300k etc.
Product failure: There are some great writeups discussing the various problems with the 4l60e. Under normal, granny use, they never materialize. But if you drive it just so , they show up (check ball hammering, cracked piston etc). When rebuilding these, you might as well build with upgraded parts so the the just so usage does not recreate the problem (upgrade separator plate, metal piston, etc)
For the third category: racing, towing, Jack rabbit, we're looking at some custom stuff to adapt to the specific needs. Custom includes upgraded parts as well as tuning the shift points to match the parts and driver. E.g. Vette servo to hold the band better during towing or racing.
The basic transgo kit ends up bridging both category 2&3. It attempts to easily fix some failing product, and tries to change shift points with hardware. For the weekend warrior, this might work dvr fur you, assuming you are driving it just so, once in a blue moon.
I had suggested the sonnax stuff as it was originally more focused on fixing the product problems, rather than special uses problem. They do have upgrades for special uses as well.
When installing/removing kits, there are replacement parts (ie springs) and modifications(ie drilling). Replaced parts are tossed and modifications are permanent (and may not work well with a item oem part). So, you can't just remove the shift kit unless you have the original parts to put back in. And besides, the original symptom being masked b the shift kit may return when that part of the kit is removed (ie 1-2 bump).
Can you stick a 4l65 valve body on a 4l60 - I'm not a parts expert, but gut feel is no unless you are a tuner. I know builders buy specific year range valve bodies typically.
Sent from my XT1053 using Tapatalk