an XR2i loom, is the same as an OFAC loom, you need to cut 1 wire. To convert it to OFAB, you have to move 2 wires on the ECU plug, and thats it.

The XR2i has a seperate engine loom, its about 10 wires i think to connect it through to the car, BUT the ECU will have to live in the engine bay, which is ok as long as theres not going to be lots of damp in the engine, if your car lives outside you may suffer in wet weather.

You can use a trigger wheel on the crankshaft pulley and mount the CPS there, otherwise u will need to drill your block to take the CPS and then you WILL need an EFI fltwheel.