If it is one of those double row chains, it probably could support a battleship, or at least 'ol Silver
If there is any stretch (and you do hear some slapping), a number of things could happen. And none of them are good. The chain may jump a few teeth on the cam or crank gear causing the pistons to make a mess of your valves. The chain guides get brittle and may break, causing the same to happen.
Roll in a new chain and check the rails. (mine was slapping before it broke)