what axles should i use??

[72kool]

I am in the process of turning my 72 C20 into the truck I need. the plan is to go from a c20 to a 4x4 k30 dually. It will be a custom flatbed to haul a car on and then also pull a double/triple car trailer a dozen times a year.

My question is , what axle assemblies should I look to get to handle this work load? I am looking for a pullout 6.0 with 4l80e and transfer case to use for the power plant. I am going to lengthen and box the frame for the bed I need, so fabrication and mounting wont be a concern. most this truck will be fabricated to meet my needs. just looking for advice on what axle assemblies I should use

thanks