you can switch to an IRS rear end but it is a lot of work. The rear end of the Hardbody is about 6" narrower than the 240, so you cant use the 240 rear subframe without a lot of custom narrowing work. Another option is to use an FB or FC RX7 rear end, it still requires a lot of work but it is about the right width. Custom driveshaft needed, of course.

this will give you any number of options for the rear, but the front is pretty much going to be torsion bars in the end, which sux. Id worry more about the front than the back, and also how you are going to keep the rear end from breaking loose when you dont want it to.