Your exhuast valve guides were worn out which is why you had the oiled plugs and dropped the valve. That head, cylinder and piston will be ruined. Depending on how much metal went through the engine there could be much more damage. When you dismantle the engine look at the bearings to see if metal made it through the oil system. If there is metal there then you need to completely clean the oil system (tank, lines, coolers, etc). If the bearings are clean then you might not need to do the cleaning but it would still be a good idea.
The other engine idea is a good one if you can get it cheap. If it's a running engine with the missing/broken external pieces then I'd pay around 2000 dollars for it. I'd put your external parts from your blown engine on it and run it while you rebuild yours. Used parts for 2.7's are cheap.
If it were me I'd skip the 2.7 and buy at 3.0 instead. A running 3.0 will set you back about 4-5 k but will be much cheaper than getting a 2.7 up to speed. A core 3.0 will cost about 2500 dollars and take 3k or so to rebuld yourself (assuming most parts reusable). Your car is smog exempt so you could build a nice carbed engine and get 230 plus HP. You'll be on your way to building a spec car to race in the PRC (
www.porscheracingclub.com)
These are some ideas.
-Andy