'85 Toyota, newbie question

I've got an '85 4x4 Toyota pickup with the 4-cylinder 22R engine. At some point in the future I want to fix him up and let him reach his full potential (he's got original everything, been in my family for twenty-ish years) and my biggest goal is a new engine, mainly because he's got no power and going up hills is a challenge. My question is, is it possible to put in a bigger engine, like a V6? Again, I know little to nothing about trucks so I'm just curious if this is possible as far as space/room, etc. Thanks.

People have been putting everything you can think of in these trucks for decades, Buick 231 and Chevy 4.3 V6's, 350 V8s, 302s, Celica V6s, and even the newer Toyota 3.4 V6.

So I guess the answer is, yes, it can be done.

Put a 4.3 in it