Quad mounts are about $400. Spend a couple hundred more on a Ford gas cruise control servo and throttle pedal and assembly. A donor engine will range in cost. I recommend a 94-98. 5 12 valve since they require so little to run. Fewer parts keeps things simple. You could buy an engine from an engine builder that is already making insane power if that is your goal. Junk yard 12 valves start around $2,000.
I would keep the 4R100 but run a good torque converter like one from Precision Industries. Actually, with over 500 rwhp, i recommend a BTS transmission. The NVG 271/273 is the best you can have so you'll be fine, if your truck is a 4x4. You will spend a good $4,000 on the transmission alone.
You will need a stand alone transmission controller. Baumann's is very simple, but powertraincontrolsolutions is the most powerful. Look to spend about $450 to $1,000 for the controller. Suncoast offers an entire conversion kit but it is very expensive and i've heard from one source that he was unhappy with it.
You'll need to mate the engine to the transmission. The best kit out there is destroked.com's kit which is an engine adapter and a stout 1/4" thick custom flexplate, guaranteed to over 1,000 hp. With that kit, you will use a Ford 6. 0 starter, which spins better than a Cummins or 7. 3 starter. ATS is one of his dealers so you chould call them for prices. The 6. 0 starter is probably cheapest via eBay.
Lots of little things like adapting fuel lines and coolant hoses have to be considered as well. If you plan to do this yourself, you'll need a hand at some points. You may have more costs like driveshafts as well. Labor at a shop is hard to guess, that's what they're most likely tell you.
To make that much power you'll spend close to a grand on a set of DDP stage 4 injectors. Between $3,000 and $4,000 for compound turbos. Injector pump mods will vary depending on what you start with. You'll probably need a head gasket, fire or o-rings, and studs to keep that much power safe. Machine work can be pricey.
That should get you started on how to research your buildup. Most answers can be found by searching the forums here. Lots of opinions, lots of experience.