Welcome to Electonics 101!
Your best bet is to start with the transmission. DTT it all out so you will not have any trouble with it. Then answer these questions...
1. What kind of fuel pressure gauge do I want (I would go mechanical) and is the lift pump enough or do I need a better system? Also what kind of FUEL PRESSURE, egt, boost, and transmission temp gauges do you want to look at?
2. which injectors are right for what is to be done with truck? (injectors are a good source of power and smoke!

)
3. What kind of box do you want? (in cab adjustable w/wire tap, or underhood plug in type)
4. How big of a turbo do you want to buy or are twins right for you?
This should help you some and looking back I wish I had done things differently, but remember gauges are your best friends!
Hope this helps you some Dan