If I was building it and had the rolled truck at my disposal. I would swap out the complete drivetrain. Front and rear axles, Rear Suspension. You will have to do custom front suspension though but it will be worth it. But this is the way I would do it.
If your taking the time to build it. You might as well build it right from the get go. I know you said don't give you flak about keeping the 44. But come on man that 44 will break pretty quick from all that torque from the powerstroke.