Engine swaps?

I currently have the 4 cylinder 3rz-fe paired with a manual transmission on my 4runner. I love the 5 speed, but I hope to swap a more powerful engine in the future. I could just go with the 5vz-fe engine that was offered in the higher trims, but where is the fun in that?

I've seen people put 2UZ v8 engines in their 4runners, I'm not looking to get that crazy. Also its extremely difficult to pair a manual transmission with that engine, a non negotiable for me is it must preserve the manual trans. I also have seen people swap in 2JZ I6 engines in their 4runner, which I assume can pair with the 5 speed. I prefer I6 to v8 or v6 because its a middle ground between i4 and v8 in terms of fuel consumption, reparability, and smooth operation.

Anyone know of other engines I could swap in a 3rd gen 4runner (especially I6 engines)?

 

If you don't mind going GM a chevy 4.3 is an option. Marlin crawler makes a bell housing adapter. I have a rebuilt 4.3 on an engine stand to replace my 3.0 when it gives up the ghost.


Edit: advanced adapters has the bellhousing adapters. Not marlin crawler. My bad