Size wise, no problem. It's got plenty of headroom for you. As far as comfort goes, it's not the most comfortable ride - but it's a utilitarian 4x4 not a Cadillac. Some come with bouncy seats which help a little.

Engine choices are a bit more limited. Raider, Montero, Ram D-50, and Starion/Conquest are direct bolt ins. The 80s Dodge /Plymouth minivans have these engines, but I believe that there are some minor differences that would prevent a direct bolt in - not positive on that. The Caravan engines have been discussed on here so you should be able to search the answer for that out here or in the archives. The Mazda 2.6 are very different - exhaust on the opposite side and will not work without swapping over the fuel injection and computer.

A lot of people have been doing engine swaps in these vehicles to enhance performance and get better parts options. The Starion/Conquest turbo engines are a direct fit and give you a nice boost in HP. They bolt right up to your existing transmission but you'll need to swap computers and wiring harnesses if you go the turbo route. Non turbo is a direct swap. Other people have been doing complete drivetrain swaps to other engines like the 4.3l. It's more work, but there is a lot of experience to help you out if you decide to go that route.

I believe there's a company in Dallas that sells rebuilt shortblocks for $500. Clearwater Heads sells new castings without the dreaded jet valves. The Carburetor is more complicated than most, but some people on here swear by it if they can get a properly rebuilt one or have spent the time to learn it themselves.

The 2.6 has a tendency to crack it's heads when it overheats. It's very sensitive to overheating. It's possible that you can use your existing engine and just swap the head. The block is pretty stout. In any case, check out your radiator. It's possible that it needs to be bored or replaced which is what caused the engine to go in the first place. It would really suck to replace the engine and then kill another one.

Good luck with it. I love my SWB Raider!