A few years ago, I had a 1991 Ford Ranger with a 4.0 V6 that was acting up too, so I decided to put a carbed 302 V8 in. There are some conversion kits available for that so I ordered the kit (radiator, trans adaptor, motor mounts, headers, etc.). Not sure if kits exist for Yotas or not, but I'm sure the engine compartments of the Ranger and 4Runner are pretty close to the same size.
It was a total pain the the butt. The engine fit pretty well, although it was a tight fit, but the accessories (A/C comp, power steering pump, etc.) all had to be modified. Not to mention the plumbing and wiring issues. That's one conversion I wouldn't do again!