[Lemming]

Yes a slippery slope indeed. I did this with a 944, started with a supercharged 3L 986 engine, then LS1, followed by an LS3. The car was fast and fun, but it was constant work and $$$. Brakes were one of the biggest issues for my build, since once you go with an LS, the brake booster no longer fits. This should not be in issue for you, but you will likely want to increase braking (calipers, rotors, etc), especially if this is a track car.

Now, once you are tired of the car, you will likely sell it for much much much less that you have in it. I could not give my 944 LS3 away because it scared the crap out of everyone that test drove it (525 ft lbs and no nannies). I ended up having to part the car to get some $$$ back.

In hindsight, would I do it again? NO.