66 GMC Heavy-duty 1 ton(1-1/4 ton?) Crew cab build

[mehtwo]

I'm in the planning stage of building a 1966 GMC heavy-duty 1-ton(maybe a 1-1/4 ton?) crew cab dually. I want to use a 478 GMC v-6, a fuller FSO-6406a 6-speed manual O/D transmission, a dana 70hd or dana 80 rear(with 3.55, 3.73, or 4.11 gears). Because the 478 weighs a lot(925 lbs dry!) I wanted to know if a 73-91 1-ton coil spring suspension and frame are stout enough for this engine and trans. If not, I would like to know if a p-30(?) front suspension and frame would be sufficient using either the coil or leaf spring front end. I've been partial to the 19.5" wheel with the 5/10 lug on 7.25" pattern, but it's not absolutely necessary. I'm looking at using 32-33" diameter tires. I want to use this rig strictly for towing 22,000 or less pounds cruising around 65-75 mph on flat land. I plan to use this rig to replace my 86 chevy crew cab 1-ton dually that has a 454, th400, 4.11 rear. The bottom line is that I want an older GMC equivalent(more or less) of a new f-450 pickup. Any help or advice is greatly appreciated.

Mike

Long live the V-6!!