Sounds like a way too cool project for words. My brother my has our dad's 55 F-100 that both of us drove to school, took camping, raced (it had a 364 Buick Nailhead in it that he installed in 1966). He drives it regularly and he says the biggest mistake he made was putting what was popular at the time with F-100s a Plymouth Valare front end. He wishes he had done a nice dropped axle instead, especially with the power steering box, he has had nothing but trouble with that.
That truck was featured in Rodders Digest issue #32.
Our dad would have been proud. He missed seeing it done by only a few months.
Funny, another project he has is his 1939 Ford Coupe that be built in the seventies. He sold it about 25 years ago and just bought it back, found it on ebay in Georgia and had it shipped to California. One of the changes he is making is removing the crap aftermarket disc brakes they put on and putting the 40 Lincoln drum brakes with Buick finned aluminum drums that he had put on it 25 years ago that worked awesome!
Honestly, it sounds like some basic changes are all you would need. But think about it, and remember about the "saving money" thing, you know you WILL rebuild that whole 2009 GMC, you KNOW you would pull it apart and paint it and replace the ball joints, shocks and bushings and all that, you know you will, you know you will want it a little lowered and get dropped spindles, and dearched rear springs, you know you will, it won't save you a dime over modifying the stock frame if you want to go that far.
I have to tell you, I had a Camaro frame clip under my truck, one day a guy at work bought a nice old AD with a dropped axle, the stock motor with a three speed. It was painted nice, just a super nice truck. One day I drove it thinking I would confirm that I HAD to have that Camaro clip. I was sickened, blown away at how NICE that sucker drove! OMG I remember thinking how it felt like an old S-10 (this was before the S-10 swap became the norm.) I went home bought a stock frame and sold the one I had put the clip on. I wanted old school, and I had already ruined my rad support and inner fenders (one of the only parts I still had from the $200 truck I bought in 1974 at 15 years old with paper route money.) I will have to patch those inner fenders up before I use them damn it. I do now have the plans of running a 49-52 Passenger car front suspension (already bought one) as the theme of the truck is a 1952 Motorama "Cameo" with a Corvette 235 Six motor in it. And that is the only reason I am running the independent but at least it will bolt in on the stock frame.
Anyway, keep thinking and make the best decision for YOU on that very cool piece of your history.
Brian