Dave,
Welcome to the bolt. It sounds like you have a plan for your truck but need the details fleshed out. There are several good IFS systems out there and some good deals such as free freight. Look on ebay for a TCI IFS kit as I see some out there pretty regularly. The price is about $1,600 but I have seen others in the magazines for a bit less.
For a rear axle you might consider either a GM 12 bolt truck axle or a 10 bolt from a 2nd generation camaro/firebird. I think the outside to outside dimension that would work well for a task force series truck like yours would be 60-62 inches.
Before you go too far I would suggestion you make a build plan that specs out what you want to do and the order in which you plan to do it. This will keep you from jumping around.
Keep us informed as we like to see other peoples efforts.
