Congrats on the new purchase. Now go smack your friend around for leaving that bike outside. It's good to see that it still has the low exhaust. It really doesn't look that bad in the photos.
There are fewer and fewer of these bikes around. There was just an auction on eBay with one complete bike that had been modified to high exhaust and he had a parts bike that would probably never roll again. That's two fewer bikes in this world.
Very, very rare beasts indeed. Looking forward to getting the serial number from yours and seeing more pics.