Engine Knocking is also caused by the early detonation of the fuel.  This occurs from having a low grade fuel in a motor with a higher compression ratio and the fuel detonates before the spark plug fires (Essentially becoming a diesel with really bad timing).  The effects can range from bent con-rods to damaged crank bearings to holes burnt into the top of the pistons.  It typically occurs under WOT (wide open throttle) at low rpm's in the presence of a high heat load, or when the motor is really lugging.  

Typically you want to use the following rule:
92 Octane: no higher than 10.5:1 compression ratio
98 Octane: no higher than 11:1 compression ratio
105 Octane:  no higher than 13:1 compression ratio

Warping the entire block is not that likely.  However, it is easy enough to warp a local area in the block, because localalized hot spots will occur when an engine is overheated.  Typically cylinder bores will warp, especially in thin wall castings of a Chev 350.  A Chev 350 cylinder walls will range between 0.075" to 0.090" thick due to the draft required to pull the core during casting.  If the engine is bored 0.030" over, the wall thickness can drop to 0.060".  For all practical purposes, this is considered the limit for ductile cast iron.  I have known a few people who have tried going 0.040" or 0.050" over on a 350, but the engine only lasts for a few thousand miles before the cylinder walls warp enough to cause a drastic drop in compression.  It is also possible to warp bearing surfaces (Such as a couple of certain V-Twin's at work right now, but that is another post) if the heat is localized in that area.  Flatheads are notorius for warping the deck and area round exhaust valves to the point of cracking, since that becomes a hot spot.  

I apologize for the long, rambling answer. (I can't help myself)

Good call!

FYI

Surfing the Internet for part cost so I can start building my 27 T roadster P.U., and came across an interesting site.

www.austinrodshop.com

Owned by Ken Austin who is repopping numerous Ford flatmotor intakes.
4 carb V8, Ardun, V8 60, Lincoln V12.  Very good prices.

Hello Everyone,

  Ryan, Debbie and I appreciate all of your support and kind words.  I just would like to let you all know what happened.  Monday (3-06-06) night our shop caught fire around 6:00.  The place proceeded to burn to the ground as it was a 40 year old wood building.  Two of our rods were in the shop that night.  Ryan's '58 Chevy pickup and Debbie's (my fiancee's) 1929 Model A 2dr Sedan were burnt to a crisp.  
  The A may be salvageable as it was still in bare metal and wasn't near finished.  I know that I can save the frame, '53 flathead, and axles, but the body and transmission were pretty badly damaged. The body is really warped and we haven't decided if we want to go through the effort of pounding it back into shape, or finding a new body.
  The '58 didn't fair nearly as well.  The loft that was above the truck collapsed onto it and crushed the box and the cab.  Ryan had spent the las 18 months making numerous modifications and upgrades, and was really looking forward to getting out in the truck this summer.  All was not lost though, as you may see the Pontiac mill show up in Ryan's T coupe (stored in an adjacent garage) sometime in the near future.  
  The fire also destroyed most of our tools, numerous manuals and vintage parts, including 9 Holley 94 carbs, 2 Strombergs, a '40 Flathead V8, '57 9 inch rear end, and a '67 Dana 44 rear end.  
  Thanks to the hard work of the EGF FD, Ryan's T coupe and his HD Sportster were spared, along with my 1951 Ford F-1 and a friends 1950 Dodge.
  Hopefully we will be rebuilding this summer, and will be back in action soon.

Thanks again.

Adam, Ryan, and Debbie