Nine second Phil had a 1969 340 block that had one lifter bore,#5 o r#7 intake, that wasn't machined properly from day one, it would eat that lobe after around 15,000 to 22,000 street miles
On your friends block I would remove the timing gear and rotate the cam and lifter by hand or maybe with a big drill motor to make sure the lifters are all rotating well
If they don't spin well have the block lifter bores bushed or go with a roller cam and lifters