Update:

I am no longer going for a massive upgrade in power, as this truck is not going to be doing any towing any more...

I bought a Ford F350 Flatbed tow truck and am getting rid of the trailer. The Mazda pickup will be a daily driver/offroad vehicle.

So, since the 4G63 Wideblock to 4D56 swap is a bolt in affair it looks like I'll go this route barring a few concerns:

1.) How easy is it to get this engine in the states? (I know importers that do performance engines for sports cars, but I know of none that do diesels...

2.) How easy is it to get repair parts for these engines? I don't want to be down for a week waiting on parts to be shipped from overseas.

3.) Is there a way to connect a vacuum brake booster to this engine? A vacuum pump or otherwise?

And then one last concern that isn't so detrimental:

Has anyone bolted a York type compressor to this engine? York A/C compressors are popular for converting to be air compressors for on board air systems. Are there places where additional ancilary components can be bolted to this engine easily?