I had a 406 that I bracket raced for years. 5.7 rods, 12-1, roller,ported bow tie heads. Wonderful combination for a 3000# bracket car. Ran 10.40s and lasted for years and years - rings bearings and valve springs was all it ever needed. Then I got into DOT index racing and using nitrous......... 3 blocks in 3 seasons. Cracked cylinder wall was the main culprit and one cracked between the steam holes and the headbolt holes. none of them ever got hot either. Now I look back and think about all the money I spent machining those stock blocks which could have paid for a good block.
I now have a Dart little M. So yes, a stock block is fine to a certain point.