[dsraven]

I recommend to take stock of what you have on an actual list. make another list of what you need, going by what has been posted here, then make another list of what you would also like to do, stuff like the dual master cylinder, possibly power brakes, etc etc. then compare notes of what you have compared to what you need to make it go in a v8 configuration, then once there add on whatever else you can afford. I don't recommend tearing a bunch of stuff apart and thinking this is going to be great and you will get it done in a weekend or 2. that usually ends up in a bunch of stuff taken off but not a bunch of stuff actually put back together for a long time. sometimes never. you look to have a really nice truck there so do the evolution a step at a time.
-engine mounts, original mounts would be easiest
-bellhousing, new rubber mounts, flywheel, clutch fork, linkage to pedal, tinwork
-starter that fits the flywheel
-wiring for the starter since the old "step on the starter" pedal isn't gonna work. a simple push button tractor switch on a bracket under the dash would get it done and later could be replaced with a new ignition switch that has the start function.
-wiring for the distributor since it likely has an HEI unit so it will need a larger wire to feed battery voltage-not the original wiring that has a ballast resistor in the line and is also a smaller gauge wire that won't support the current draw of the HEI requirements
-wiring for the alternator since the 350 probably is using a 10SI alternator, not the old generator. there are lots of "how to's" on the web for wiring these and they will be waaay more reliable than the generator
-possibly wiring for an electric choke since the old rochester carb from the 350 will likely have one. again, check the web on how to wire that up if it is equipped that way
-throttle linkage. check the assembly manual for how the original set up looks or, if you have a carb that was operated by cable, you can install a new pedal and connect a cable operated accelerator (manual linkage will be easier. if you see what it should look like you can likely fab up something)
-exhaust manifols, Y pipe or whatever you decide for exhust system
-driveshaft should be the same if you use the stock trans from the old inline 6
-water pump and rad hoses. the 70's water pump may have a different outlet orientation but a bit of ingenuity can easily overcome that
-flush out the rad, inside and also through the fins, to ensure the "new" engine isn't gonna overheat
-take pics before and during dissassembly so you can "remember" how it used to look when it comes time to put it back together

I usually try to use old cake pans or plastic wash basins whan I take stuff apart. one for the under side and one for the top side. that way the fasteners stay where they came from. also, if you take the fasteners out to remove, say, a generator. install them back into the part so you will know thats what they are from and what orientation they go back together.
mr48 makes great point. start with a clean unit from the top and the bottom. some cleaner that I have used with great success is Catrol super clean. it works well but don't let it sit on painted or aluminum surfaces, like fenders or mag wheels, for long. a pressure washer or the local car wash would be great, wash from the underside, then the top side. wear safety glasses. it makes things so much easier to work on when the parts are clean and your hands and tools arent covered in grease and dirt

post up lots of pics, you have us hooked now. lol.