What You Need:
Engine Harness
XR-2 Sensors
XR-2 intake with fuel injectors
Pedal box, and cables
turbo lines
XR-2 Transmission with the half-shafts
Intercooler, and all piping included
XR-2 computer
Things to note:
You're base Capri engine has a higher compression ratio I believe its 9:1 over the XR-2s 8:1, but im not exactly sure on the ratios its been too long. Just be careful with how much boost you throw at it, because higher compression ratios cause detonation. Also the reason you need the sensors and the XR-2s engine harness is without it the engine will not run, or will have the check engine light on.
In the long run it might be cheaper to just buy a XR-2 unless you want to be a bit unique.