Brandon is right, this is a very broad question.
Possibly the most common swap would be the 3.4L Chevy V6.
But I've seen Supra Engines (7M-GTE), Chevy 350s, Mustang 5.0 L (Brandon), big blocks, small blocks, 3.0 L Toyota, 3.4 L Toyota, even a 388 stroker.
I mean hell, at our shop we have a 4.3L in a 81 and a LT1 Camaro 350 Tuned Port in an 85 4Runner.
Many swaps are possible however Toyota trucks are not known for having alot of room to play with for swappen in larger hamster wheels. 79-83 Trucks are of the least amount of space. Another concern would be drive train in which case many companies are now offering adapters to go from GM, Ford, and Dodge transmissions back to the stock Toyota transfercases.
In terms of hop'n up your 22R, this is the cheaper alternative (to an extent) but will yield considerably less in the end.
If you do alot of trick work to a carb'd 22R, put on a 20R head, shave and deck, run larger valves, cams, headers, webbers etc. you may be able to push past 150 or even 160 HP, but it will take alot of work and proper tuning to get that result.
Also, it largely will depend on why you want more power. Is it for towing? Speeding? Crawling? Mud Bogging? Maybe Racing
Consider weight too. If you like to run in the snow, I have seen V8 autos do horrible in the snow because they have become a heavy sled and the 4cyls can stay on top of the snow and get much farther with less power. sometimes i guess....
Let us know what your plans and goals are,
Regards,
BigMike
