its pretty easy. the only issue is that with 82/3 door handles, there was less need to compensate for space since the handles were pretty self isolated, whereas 1984/5 handles actually have a large hinging section that goes up into the door above the handle inside. 82/3 door skins have a very minor metal flange that you will need to cut away if you plan to swap later gen door handles into them where the 84/5 door skins have this flange cut away from factory. also note that the door mechs need to match the handle year as well as the mechanics in general for the handle, since they function differently and have different door lock bars (early ones have a large threaded bar, later ones dont), etc.
I personally love the later model ones as they are just a bit more easy on the hands when you have gloves, but more importantly, almost never break. Going back to the door skins inside, you can use a tiny cutoff wheel or even dremel tool with a cutting disc to cut that section off then pull it away.
You might need to use vicegrips to pull that flange into the doors outer skin to clear the handles, but if you do, use a big wooden board of some sort unless you want gnarly dents around the handle. i dont have pics of the two door designs but its a slight pain.
i may do a more formal writeup on this very subject once i get around to learning imgur. another thing to mention is that if you have electric door mechanisms for locks, but have a manually equipped car without electric locks, they still work. Toyota electric locks are designed almost exactly like aftermarket door poppers (ie viper alarms, etc) so you can unhook and even remove the lock actuator if you wish. (Kinda heavy, i deleted them)