When you're selecting parts for your build, be honest with yourself. Do you still have any toys from your childhood or did all your stuff end up broken? If you fall into the latter category you might be a little rough on things!
I'm leaving my 7.3L pretty much stock. If I was shooting for 400-450 hp I would run the upgraded input shaft, billet converter, iron drums, and steel planet carriers. I'd also make sure you have the newest style pump. The choice of clutch material seems to be a toss up. Some builders like only factory Ford clutches, some opt for the red frictions. Nobody I asked used the blue clutches (I gather they are more drag race oriented since they were highly recommended for my C-6 bracket car).
You can opt for a BTS valve body or a DIY
with Sonnax or Trans-go parts. Don't forget that you need to coordinate with your selected chip vendor so you get the right computer tuning for the valve body/accumulator body you select.
I did a lot of shopping in the Sonnax catalog, they offer several fixes for the problems that plague the E4OD/4R100 trannies.
A stock 4R100
rated for 1000 hp? I thought they were shooting for it to handle 1000 nm (about 750 ft-lbs). They fell a little short of that I think. I'm sure I read on here that a 4R100
output shaft won't hold 600 hp. I believe Mark posted that and he would know.
Don't take it apart until you have a factory shop manual on hand and at least a torque wrench that reads from 0-150 in/lbs in addition to the "normal" hand tools. You'll need to buy or make a couple of compressors like what's shown in the thread Ol'Blue referenced. Take pictures as you go of how things came apart. My build is progressing over several months and I refer back to my photos of where each little valve, spring, bearing, and clip goes to aid my memory.
If money isn't very plentiful, you might need to scale back your expectations. I know what I've spent so far on my build and I could see where a guy might easily spend $2k or so for what you're looking at here by the time you get done with machine work and all. Stephen