Stock 5.2 Vs 318 with XE262

I get what you're saying. I agree.

I just think swapping a magnum 5.2 for a basically stock 318 with a cam is an exercise in futility, or even a step backward. At best you'll have a 318 with weaker low end torque and possibly matching high rpm power.

The area under the curve probably still favors the magnum. Throw an aftermarket hydraulic roller for the magnum in the mix and it's game over 318.