WElcome to the forum. So ill shed some light on this as I just finished my lowering job, of course i went with the "extreme" kit. Here is a link to the site I bought from,
http://www.performancesuspension.com...ring-kits.html
Would I buy from them again? Yes, am I satisfied paying them a buncha money, yes. Are the parts of quality, yes, Do you have good customer service? Yes, from the million times I called them they were very helpful...
Now to shed the light.... Be prepared to replace stuff. Its one of those things, that your already there so you may as well do it. Do not short cut yourself, if you see that it needs to control arm bushings... take care of her, and replace them

etc etc etc
Your description of how low you want is basic, You can get that with spindles, and rear lowering shackles and removing any helper leafs. Just be sure that you will be happy with that minute of a lowering job.. I have read and read and read too many people just not satisfied with little lowering jobs. Here is a pic of my truck, lowered 6.5 front and rear is 7 inchs. Now its a little extreme, but if you like it enough ull go with it
Good luck!