I’ve been doing a lot of research on these swaps and I have a 1990 Toyota pickup with the 3vze and am wanting to swap it out with a diesel. Any suggestions on the best motor to swap with the least modifications. I’ve researched the 1kzte, 2lte etc

 

That's what I ended up starting with (I never did anything with my 22re). In my opinion the 3L with a turbo is a better option than the 2lt. As far as I know, if you don't want to do a ton of wire pinning, the only way to put a 1kzte in is to swap the injection pump to a Mitsubishi 4m40 pump. It's the same case just without all the electronics.
If you're looking for reliable power, and only minor modifications a 3l with a turbo is your best bet. The engine is single-wire ignition, you only need to move or modify the engine mounts a little (3vze application) and bell housings are available on eBay. I'd build a better exhaust manifold for the turbo though.