You're goals are similar to mine. What I did is figured out what the biggest differences were between the suspensions in trucks offered today and what we are working with. A truck can be made to handle, it's not cheap, nor easy but it can be done. And when I mean handle, I mean go toe to toe with a newer sports car. Our two biggest problems are weight and CG. What ever you can do to lighten the truck will help performance in every respect. The CG we're sort of stuck with. You can only go so low before you have clearance problems and as mine will be a daily driver I don't want that hassle.
With the front there's is not a whole lot that can be done. The 4" drop will be good. Get good gas charged shocks designed for the drop and get the biggest (as in diameter) sway bar you can get. I haven't researched sway bars yet so i don't know what options there are. There is a factory bar that can be bought but I'm not sure of the diameter. There has to be something out there that can be modified to fit our trucks though (in a larger diameter than the stock unit). Another thing is look into some aftermarket A-arms. Tubular if possible (to save some weight and they look cool
. Make sure that after your drop the lower A-arm is parallel with the ground. A-arm suspension work the best with the lower arm this way. Use poly bushings where ever possible, especially on the sway bar links. The only other thing would be if some one makes some bolt on A-arms that are set up for coil overs. To do anything else to the front suspension will require fab work for mounting custom arms or buying a crossmember kit. As far as the steering a rack and pinion is the only way to go (again in my opinion). I just don't feel that as far as response and feel, that a gearbox can compete with a rack. And most every aftermarket kit you find uses Tbird/Pinto racks including Jim Meyer and Progressive Automotive. (I will discuss these two companies at the end.) I don't think it would be too hard to adapt a rack to a stock crossmember, the hardest part will be finding one with the correct dimensions. Again this shaves some weight also.
As for the rear there is many directions you can go. But here I decided to stick with the trailing arm suspension. In theory this is a very good suspension set up. Both for handling and launching. A lot of aftermarket suspension companies are making truck arm kits for the pro touring guys. I believe it just wasn't engineered to fit our trucks as well as it could have been. You said you were going with a 6" drop here. I know some will disagree with what I'm saying but you MUST get shock relocation kits and a adjustable panhard rod. Shocks are meant to be near vertical and when they are layed over they cannot do their job properly. Some will say you will need a C notch others will say you won't. I can't help you there but you definately don't want the housing hitting the frame so it might be something to check into. CCP makes a bolt in C notch kit and a coil over kit that I think is a bolt in also. If you can do it I would suggest making your own adjustable panhard rod as opposed to buying one. You could easily make a 1 1/2" diameter or so bar. A couple heavy duty Heim joints and your done. Any other option (i.e. 4 link) will of course require some fabrication and/or welding. I went with a HTH kit which comes with a BIG adjustable panhard rod. It also has a cossmember you weld in so that you can adjust the angle of the bar to keep it horizontal (or close to) it which is where you want it. It also has screwjacks so I can adjust the ride height and and preload for the drag strip. I won't go into more here but if you would like more info let me know.
As far as the Jim Meyer frames I like them but I wanted to stay with the trailing arm rear and they come with 4 links. Progressive Automotive makes a nice kit using Vette suspension components but I didn't like the spindle adapter. Probably nothing wrong with it, but it just didn't give me warm fuzzies. I figured I'd go the tried and proven Mustang II route and I'm definately impressed with the Fatman Fab's kits looks. I figure I saved at minimum a 100lbs. Got my rack, nice polished coil overs and tubular A-arms. Plus 5" of drop with out spindles nor compromising ground clearance. I will then mini tub it and that should easily allow me to run around a 14" wide wheel (plus or minus, haven't got the 8.8 under there yet). That's my .02 in a nutshell or two. Good luck.