413 motorhome/truck/industrial motor "chat"

So why do you like these engines so much? Do they get good mpg or are they just really long lasting? I assume the intake side of the heads is similar to a regular big block and the exhaust side is different to allow better cooling?

If the block really is an underbored 440, surely the easiest/cheapest thing to do is bore it out to 440 size?

Do regular big block heads/timing cover/intake etc swap over to this motor?