Take the head off, send it to a machine shop for a rebuild and street-level port n' polish, plus any after-market parts you'd like to add (cams, valve-train, etc.). While that's being done, source yourself a clean, low mileage LS or GS-R block. Put freshly re-built and beefed up head onto the new 1.8 liter block. Done. Add boost if desired.
Seriously though, if you plan to boost in the future I'd probably skip the Type R swap. The Type R engines are designed to be high-revving N/A screamers. In factory form they're not really suited for boost...