1981 K5 Blazer build questions

[Patriot]

I have a 1977 K5 and a 1981 K5. The 77 is completely stock with the factory 400 motor. My 81 on the other hand is going to be my trail rig. I have a few different trucks and I will be using my 79 1 Ton 4x4 for parts for the trail rig.
Now my questions:

Will my Dana 60 bolt up to my 81 without any trouble?
Will the heavy duty leaf springs from my 79s rear work for my trail rig? It has the max amount of springs because it used to be a Tow truck.
Are all SM465s the same, same gear ratio and spline count??
Will I have to use the Blazer springs and just bolt up my Dana 60 or will the truck springs work?
I know alot of you guys seem to like the Corp 14 Bolt but my donor truck is a dually and I have a Dana 60 rear posi that I can use for the trail rig. Are these not strong rear ends?? If they work for the front why not the rear??
I will NOT be an EXTREME trail rider. Just Highway and sometimes a ride through the Black Hills.

What say you fellas??

Thanks in advance fellas.

Patriot---