You ask a popular question. You can find more info with a search on this forum, but below is one of my responses from some time back. In a nutshell, get that Hot Rod magazine and I think you’ll find what you’re after. The URL helps too.
John
Nov 14, 2020#19
The June 2019 Hot Rod magazine has a helpful article about the 700R4 and similarly-controlled transmissions. It includes some internal upgrades to improve resilience, etc. There is also good information at the link below, which focuses on the critical carb linkage required to pull the TV cable properly on acceleration (sounds harder than it is, as others here have mentioned). I have a 700R4 with the mods suggested in the Hot Rod article in my avatar car - works well.
John
http://purplesagetradingpost.com/sumner/techinfo/700R4p7.html