This is nothing but opinion, but...
If I were going to put the time and energy into a forced induction setup, I wouldn't leave my self open to any potential PREVENTABLE breakdown. Adding more stress to a 6 year old, 104K mile engine seems like asking for trouble. I'm not saying that it couldn't handle it for even another 50k miles, but if the extra stress makes a minimal problem (-1 psi in oil press, cooling passage blockage, slight blowby under normal compression, etc.) into a MAJOR problem, you'll be spending the extra $ sooner. I think it would be worth the risk it on a 25-50k mile engine, but assuming you even have only used up 2/3 of the engine. That last 1/3 is going to wear out a lot quicker.
You don't necessarily have to tear down the motor, but at least check out some of the indicators - compression test, maybe check the bearings, (I'm not a mechanic, so I wouldn't know what to check for sure). Of course, as long as you're in there, it might be better to replace some things, but you wouldn't have to.
Look at it as cheap insurance for when you mash the pedal. You'll know that the motor is up to it.