Congrats on your new acquisition.
Some common places to look for aftermarket and upgrade parts are
Low Range Off Road
Mikodaindustries (tons of OEM stuff)
I know for many folks a SPOA (spring over axle) works well and all the goodies to do it are readily available.
What I would suggest seriously considering what you will want to do with it, what it will need to handle, how and where you will drive it, and then consider your build to suit those purposes. Common engine swaps are to a Suzuki 1.6L from a sidekick, Google is your friend