[84LX89GT]

It's pretty easy from what i hear to drop in a 351 instead of a 302. Here's are the only things that may need attention:
First off you need the right flexplate for the imbalance of the engine and has enough teeth that matches up with the starter....but that is easy.
If you want to keep the stock hood you'll either have to find a low-profile dual plane intake (like an edelbrock performer) or single plane intake (offenhauser makes a lo-pro 351 single plane and also a Edelbrock torker II).
The 351 has a taller deck height so you'll need headers for a 351 conversion, which is no big deal because there are lots of header manufacturers who have several 351 options for fox mustangs.
If you run the stock serpentine belt, you'll probalby need an aftermarket bracket to run the stock accessories....which are also fairly easy to find.
You may want to upgrade from the stock 2 core copper radiator to maybe a 3 core aluminum, not necessary, but a good idea.

Other than that it will fit in with no hassle, use the stock motor mounts, has the same bellhousing bolt pattern as a 302 so trans selection is awesome. You should have very little problems with that swap.

As for the supercharger, you could probably convert the paxton kit for mid 80's carbureted mustangs easily to work on what you're building. It has a housing that goes over the carburetor and the system is similar to fuel injected mustangs in appearance. That kit is a centrifugal kit. Also Vortech offers a carburetor housing for adapting one of their mustang kits as well, but it's $500 just for the sealed housing. This is centrigual as well. There are of course, the old style roots blowers out there that would require cutting the hood and are draw-through instead of blow through systems like the Vortech and Paxton kits.
I think B&M makes roots superchargers for 351's, but i can't think of any others off the top of my head.
Hope this helps,