Throttle body is easy. Just get an adaptor plate off an MK3 XR3i (the manifold already came with the triangular shape for the throttle body, but they still used the rectangular shaped tb like RS1600i and ERST). When you're still using MFI pipework won't be easy because the fuel metering head will be in the way.

The rest is just drilling holes and tapping threads to make the additional ERST sensors fit.