6,000...6,500...7,500 has been done with a stock block / rods for many years with no issues. I used to spin my stock bottom end (block crank rods) 289 7600rpm on a regular basis with a flat tappet solid cam. That junk lasted 3 yrs and I only had an issue then because of a broken stock oil pump shaft.
Too many people read shit in a magazine and have no real life experience with it. Then they spew it around like its the gospel. (generally speaking)
He didnt say he wanted to make 800hp on the motor, he said 650-700 on the bottle. BIG difference between the 2 set-ups