Small Engines (Lawn Mowers, etc.): Briggs Intec broken connecting rod, heat dispersion, emery paper

Question
I have a co-worker who ran his lawn tractor with low oil, and the connecting rod broke where it connects to the crankshaft. B & S model-type 31C777-0226-E1; code 040319ZD. There is a fair amount of scoring on the crankshaft journal for the rod. The piston and cylinder bore don't appear to be damaged. My question is, how long do you think the engine would last if he just cleaned up the crank journal a little with emery paper and slapped a new rod on? I'm thinking since the rod is aluminum, any scoring on the crank journal would wear out the rod soon. There is no undersized rod available, so you can't turn down the crank. The only other option I see is replace both the crank and rod. Thanks for any advice!

Answer
The problem is your only seeing superficial damage. You can't see the additional heat related damage done to the other metals involved from the extreme heat caused from the lack of oil. Oil is not only a lubricant as people seem to think, it also aids in heat dispersion. The entire internal engine parts suffered from the extreme heat build up. ALL the metal has fatigued. Unless a full rebuild is preformed I wouldn't even waste my time rebuilding a torched engine. Even then each piece needs to be measured, and checked for run-out.  A short block is only $450 for that engine.