I had a few 700R's in mine before I went back to manual. Granted I bought all of mine from a pick and pull so who know how bad they were to begin with, but hey you cant beat $70 with a 30 day warranty with a stick. After pulling it out the last time I realized the TCC lock up was not wired correctly so I dont think I ever had overdrive. Just make sure you adjust the kickdown cable correctly or you can wear out the clutches. The "newer" 4L60E is way more abundant now, but it will require you to tap a VSS in the tail of the trans to get it to shift properly. I am not sure if the 4L60E has its own computer or runs off another Engine ECM, but it gets its input from the VSS for its shift points. There is also a beefier 4L80E. Good luck!
There are a couple of differnet ways to wire it. You can use manual switch or a pressure switch. There are kits out there for a pressure switch. You can also run both. Just your preference.
Google 700r4 wiring diagrams and pick the one you like. Here is a you tube of one of the kits.