That machinist should never eat beans. Where he's got his head parked will result in blowing his brains out if he gets a little gassy. The basic stovebolt design engine helped us win WW II, and millions of those engines were produced from the mid-1930's to the early 1960's. Very few engines had that long of a production run, and if the design was as flawed as this self-appointed "expert" believes, why were so many of them produced?
The basic Chevy/GMC inline 6 cylinder is not a hotrod, and there are some pretty basic design features that make it difficult to run them at high RPM, but for everyday getting from point A to point B, they're hard to beat. My grandparents ran a couple of 1934 Chevy trucks from Nashville Tennessee to Milwaukee and St. Louis and back on a regular basis, pulling semi-trailer loads of beer. They installed and maintained a lot of hangovers from the mid-1930's through the early 1940's with those rigs! 216 and 235 engine are much better-designed and more reliable than those early-30's engines!
Jerry