If your considering doing this on a shoestring budget, you might want to reconsider it. If you are a good welder then it will be much simpler. If not, it will be out of your budget range. This will be a bare minimum of a $10,000 project. That is sourcing your junkyard motor and rebuilding it, doing all the welding yourself, new transmission, linkage, shifter, front suspension, rear axle, driveshaft, axle mounts, shocks, etc....
This will require some major work. Your likely looking at shock tower deletes, a new front cross member with proper engine mounts, you will need some suspension modifications. I would just do a coil over conversion since you will be 75% there with the new cross member anyway. I would just go with the mustang 2 setup like in the link DON C posted.
Then you have to think about running a big block transmission. Will you need to cut the firewall and reshape the tunnel? You will likely need new linkage as well. Depends on what you put in. You could go with a C6 which would likely fit without any issues. A better route would be to get a big block AOD, such as this one.
https://fordracingpartsbydonwood.com/driveline-parts/automatic-transmission/aod-big-block-ford-performance-automatic-street-smart-transmission-pass53133/
Then theres the rear axle. That's a ton of torque on a 8" axle, even a stock 9" will be pushing the limit of its specifications. I would go with a new Moser full floating rear end specifically built for muscle cars. Like this one.
http://www.moserengineering.com/9-Ford-Auto-Cross-Edition-Full-Float-Rear-End-Package.item
As for which block to look for, give this a read. It might be helpful when deciding which casting series you look for.
http://www.429-460.com/t120-block-info-gathered-by-djohagin
Ideally, a 4 bolt main DOVE-A block is what I would look for.