Sell your first born to a salvage yard.
Locating a donor vehicle would be a cheap solution - the engine management system must be pulled completely and relocated under your hood. At this point you can at least choose to use '92 and up components, avoiding the scarcer and more challenging '90 Renix setup. Either way, you will need the complete wiring harness under hood and at least the balance of the underdash setup, so access to a Factory Service Manual will be almost mandatory to know what's up. Then, the various sensors, many already attached to a donor engine, are next, an appropriate radiator and hoses, ignition system, motor mounts, power steering hoses, A/C mount and hoses to fit the new motor, fuel injection pump and lines for the tank, air intake system, and electric fan setup. If any of the compatible items from your present setup will work, great, just don't assume anything will be the same. Do as much as possible while the engine is out, starting from the fuel pump and work forward systematically, take pictures with a digital camera, and keep in touch so we can keep giving pointers.
Most of us haven't done it, including me, but it can be done. You need to ask yourself if maybe swapping your mods to a runner wouldn't be easier?