First, welcome to the forum, there is a lot of good information on here, start reading and studying and you will realize why some of the stuff you are asking is not quite inline with what you actually have. Determine the end use of your project and create a plan to achieve it, stick with the plan and just spend your money going in one direction to the end. Too many times people change direction mind stream and end up spending money twice. Although the slant is a usable powerplant it can be expense and still not end up with power and balamce of a basic small block, I would reconsider that decision but that's me, converting the suspesion to a coil over type is doable but most find the bang for the buck is lacking, the torsion bar front end can be very effective set up right. Front disc conversion is very common for your set up but rears will need to be aftermarket due to there not being a factory swap that I am aware of but I don't know everything out there. Trans swap is doable and would be fun in my view but again the auto can be enjoyable in its own right. Most Mopars are set up with a K-Member (front sub-frame if you would and it is removeable to recondition as you please, they are unibodies and the frame rails are integrated into the body and cannot beremoved and replaced with out major work and is typically not necessary, when it is neceessary you are usually better to find another car to start with, only special cars are worth the effort. AMD makes the best sheetmetal out there by most accounts and I am personally a fan. Soft parts are available and in many cases is just a matter of pciking your poison, I would wait til the time of purchase and ask what is the best available at that time for each particular piece.

In short, read, study, plan your build and stick to your plan.