From your requirements, ANY 4Runner will do the job.

With the right skills, time, and money, you can put any engine in any car. No V8 will just drop right in though.

All you need is IFS. It will ride much smoother than a solid axle and is plenty capable for what you describe.

I'd recommend a 1986-1989 4Runner. They have the removeable top. 4cy was standard up until 88/89, where you could get the V6. Both motors are great. Neither motor is a speed demon, but they will get you where you need to go. The 6cy has a little more pep than the 4cy. 4cy is easier to work on than the 6. 4cy motors usually meet their death from either a broken timing chain or being overheated. 6cy meet their death from a blown headgasket. Pick your poison. But stick with a manual trans, auto trans sucks up the power on these motors.

Or if you have the $$$, get yourself a 1996-2002 4Runner. They have a more comfortable suspension, interior, and more power with the v6. But no removeable top.

Any other questions just ask.