Only experts need apply...

Serpentine belt is better, and would be the easiest way to make this engine swap. I agree. But it does look out of place in my opinion, especially with the high mount truck orientation. Plus I would lose the mechanical fuel pump. I've already done the modern engine/fuel injection swap on another car. I want to keep this one a little more old school.

So why use a Magnum?
Availibility. Modern build quality. Factory roller cam. Biggest reason though is the best chance of building an engine without ever setting foot in a machine shop.