The standard bore size for a Chevy 350 is 4.000 inches (101.60 mm). This can vary slightly depending on the specific year and model of the engine.
Here are some websites where you can find engine specs for the Chevy 350:
* [Chevrolet Performance](https://www.chevrolet.com/performance/specs-tech)
* [Engine Builder Magazine](https://www.enginebuildermag.com/2015/09/chevy-small-block-engine-specifications/)
* [Hot Rod Magazine](https://www.hotrod.com/articles/hrdp-0203-chevy-350-engine-bible/)
* [Summit Racing Equipment](https://www.summitracing.com/search/product-line/chevrolet--gm-performance-parts-350-cid--5-7l-engines)
* [Jegs High Performance](https://www.jegs.com/p/Chevrolet-Performance/Chevrolet-Performance-350-Engine-Assembly/752448/10002/-1)