Hi and welcome to the forums!
First, what condition is your Mustang in?
Secondly, do you want headers or manifolds?
I have a near stock 460 i my 67' with a small RV cam. It moves my car with little effort so, its very fun to drive.
Either drive shaft can be reused just the length needs to be adjusted. Any local drive-line shop can do the shortening if you aren't a welder.
Now, please forgive me if i make the following sound negative or describe the swap as being too difficult to you. But, this swap can be a pain to some that expect an easy time.
I am definitely not trying dissuade you or anyone from attempting this swap. But, it can be like any swap, an expensive mess if it isn't though out first.
The shock towers can be a pain although they are spaced further apart than the older Mustangs. If your shock towers have any rust and or holes cut in them you might want to repair them before proceeding.
Which steering box do you have? The earlier 67's have the solid shaft/column and the later use the "rag joint" This makes the headers an issue in the older 67's.
In fact, the steering box in my 67 was too fat to allow my first set of (expensive) headers to clear without denting the tubes. These where part of a 460 swap kit that i bought from Ford Powertrain Applications http://www.fordpowertrain.com/FPAindex/FPA%20index1.htm
My shock towers where bowed in too much for the kit to work though.
Not sure if any other header will work in the 67~68 Mustangs for the 429/460. There might be a chance that some other manufacturer's will fit not sure.
Cutting the shock towers and plating them for clearance is recommended though, not really necessary. It helps in allowing access to the spark plugs/wires and the header bolts.
The motor stands that i had in the kit, where copies of the Boss 429 stands. These used the factory Boss 429 insulators that placed the engine further forward than i anticipated. This caused several issues. One of them was that the kits headers hit the steering box and the engine was too far forward for my tastes.
The Boss 429 used the short style water pump as the engine is moved forward in the chassis by the mounts. Now the Boss 429 was in the longer 1969/70 engine bays so keep that in mind.
Personally, I ended up trashing all of the shock towers and the crappy steering box, replacing them with a 1977 Mustang II suspension. (This is not for the fainthearted nor non mechanically inclined) and i couldn't be happier with this outcome.
I went with a cross-flow radiator with three rows and some modified brackets. The cooling department should be carefully considered as these are fairly tight engine compartments. Hard to get the heat out of them.