If you know how to use a compression tester, use it and check the compression in all 6 cylinders.
This is great advice, a 5 or 3VZ will last a very long time if treated properly. And, compression is a good indicator of that if done properly.
Everything said I agree with. I, too, have a '96 with nearly 300k miles on it. Changed very few parts. My only fear is that my headgasket is on the way out, I only know this because i left the country for a few weeks and got mucho white smoke on start up after sitting(but, ya know, it did start right up after sitting for three weeks). When I'm driving it everyday, which is all the time, I still can't tell the motors not new. It runs like it. Point being, they just keep going. If head gaskets don't scare you away, then theres not much worse that can happen to one of these motors. (there are few cases of cracked heads, and there was one guy I've seen that threw a rod.)
I would think a 4runner would be a good match. I won't mislead you though, there are issues that need to be addressed, and if whatever 4runner you buy doesn't have it documented, you need to put some money in up front to address the known issues. (Lower ball joints, radiator, and good maintenance, fluids, front brakes aren't the greatest but can be improved)
If the budget is firm at 4500, I would try to find a 3.5k 4runner and get it tip top. Then drive it worry free.
(If you do want to consider some other things, I'll put in a vote for well a well maintained pathfinder, I think they are said to be nearly as reliable.)