unfortunately TT kits for the XR3i are rare as rocking horse shit. Especially complete ones. Usually you will just find bits here and bits there.
Plust the kits runs off a carb and doesn't use injection,
even with the kit your looking at about 3 grand to fit it. Not cheap considering you could pick up a RST engine, loom and all the ancilleries you need for about £800-£1000