I would think that if the motor is for autoX you'd want something that you could get through the gears quickly - revs fast.

With that said, and the fact that you want a lot of torque, I'd say that a B20/vtec with a GSR/ITR tranny would be the way to go. I'm not extremely versatile on all these motors, but that is my impression.

Check out www.bseries.net to answer some of your questions.

Oh, and as for your question about swapping: you'll need a cherry picker (engine hoist) to do the swap and know how to wire up everything that your VX harness doesn't have. I did my own swap and it really wasn't that hard.