The thing that keeps me in my 986 and thinking about a Raby engine or egine swap is that I think the 986 is just a nicer looking car. For some reason the look of the 987 never struck a cord with me. That brings me to the best, most expensive solution of all. Rebody a new 987 with carbon fiber 986 body work.
It's a win-win-lose situation. You get the best looking Boxster and it'll be lighter than a regular 987, a great interior and drivetrain and lose lots of money.