do the engine swap and dont look back. Dont look at it as an investment, but I am sure I would have no trouble selling mine with the swap. I doubt I would get back the entire 16k I put into it however. But one drive and the induced permagrin would sell it no problem. You definitely get that "kick in the ass" acceleration with the 3.4 in the box. It is addictive, but the best part is that you end up with a Box that beats a 911. Best of both worlds. Quick and mid engined.
having said that tho I also have the "Iwanna911someday" issue....
but I have my heart set on a 993tt. Better looks and rocket thrust. And air cooled. A real 911.