How much is too much to bore out a DZ 302 block? Does a .060 over-size bore leave the cylinder walls too thin?

[chicane67]

0.060" is a realistic limit. If you are not going to use this for any serious power plant you might get by on the street......but you should have the block sonic checked. It is not really advisable to run a block with any sonic number in a performance application with less than '90'.