A 4L60E and a 700R4 are essentially the same as far as bolt patterns and such, the main difference is the 4L60E has an electronic valvebody. The 700R4 will bolt up, but your wiring will not connect to it so you will have no speed sensor signals to your computer. Also I'm not sure wheter or not the Throttle Valve cables are the same, but the lack of signal from an input and output speed sensor will likely cause some drivability issues.
As far as duribility the 700 is essentially the same trans minus all of the electronics, so it would hold up just as well as your 4L60, which does not seem to be that great. Consider regearing or at least adding an auxillary trans cooler if you're going through transmissions quickly, my last 700R4 lasted 264k miles with 33's on the truck and 3.42 gears, an old friends 4L60E made it to well over 300k with 200k on 31's and the remaining on 36's, 39's and then it finally bit the dust when the truck got a set of 44's
