How to check timing chain stretch on a V12?
 

I'm looking for some "easy" ways to check timing chain stretch on my 95 S600 (140,000 miles). I do not know if the timing chain was changed on the car, and have no way of finding out. I was having trouble with my beater, a 1987 Olds wagon with a 307 V8. I suspected timing chain problems. So I removed the distributor cap, and hand-turned the crank the opposite direction while watching the distributor rotor. The rotor should rotate almost immediately if the timing chain is in good shape. On the beater, it didn't. There had to be at least 20 degrees of crank rotation before the rotor began turning. Disassembly confirmed an incredibly stretched chain and worn cam sprocket. Can this method be used on the V12? Are there any other methods I can use? I'm trying to avoid as much disassembly as possible. I'd sure appreciate a good tech's advice / opinions.