I agree with moper on the 11:1 compression deal. A whole lot of pain for not much gain. Sure you can always spike the tank with a couple gallons of 110 at home, but what a PITA on a road trip. Most FBO's wont allow you to pump avgas into your car anymore (fuel tax issue). Also, the 11:1 pistons will most certainly have a dome, which isnt especilly good for flame front travel in the chambers. You'll make more power with a flattop and small chamber for a given compression ratio.
Now, if I had to guess, you are going to find broken rings. Most likely due to too small an end gap (KB specifies a fairly large gap due to the high top ring placement). If the rings broke, then the lands in the pistons are probably beat out. I wouldn't be surprised to see scratched bores either. So, you are looking at new pistons (whatever you chose) and having the block re-bored and honed. Plus, the cost of having the heads cut on both the deck and manifold surfaces as well as custom short pushrods. And since the engine will be apart, new main and rod bearing inserts. Re-balance etc...
Here's my suggestion (and it's just that), put a 360 shortblock under the 360 heads and put up with more power than an 11:1 318. The cost of having a 360 crank resurfaced will be quite a bit less than a head shave, and most all other costs will be the same regardless. You will need to buy 340/360 motor mounts, and a weighted flexplate to make the swap. You can always sell the almost new SFI approved flexplate and damper off your 318 to offset those costs (you DID put a new SFI approved flexplate on that 318 didnt you?)
Just a thought.