Welcome to CHR! Sounds like you have the start of a nice truck, and a good plan for it. Knowing what direction you want to go on the build is the first and one of the most important things to do and your's sounds quite realistic. I'd also go the Fat Man route on the front, and either a leaf spring rear or a triangulated 4-bar with coilovers---the reason some of these ride so harsh is the builder used too high a rate spring on the coilovers, and or has a set of coilovers with too little travel. I'm no big flathead fan at all, too expensive to put together. With what you want for performance a good crate motor (with warranty I might add) from your favorite manufacturer (Chevy has them starting a $1500.00) and an overdrive automatic will more then meet your criteria!

I also would congratulate you on knowing up front that this will be a time consuming project! So, you're off to a great start, now just plan your work and work your plan, ask lots of questions, and enjoy the process!!!!