I agree with the machine shop, any material left over from the failure will be taken care of by the filter. OF COURSE how could advice such as 'tear it all the way down and inspect\replace EVERYTHING' be wrong? That kind of advice is a sure bet and one a lawyer would certainly go with!
Cost\Benefit analysis:
Go with the machine shop, put in a roller, change the
oil and filter and get on with your life.
There is no 'good ole
oil' like we have used for 35 years around anymore.
Oil HAS fundamentally changed, it is NOT your 'daddys oil' anymore. No need to go
synthetic (can if you want) the key is the missing ingredients, like ZDDP. Thats why it is IMPERATIVE you use an oil additive that DOES contain a healthy dose of it to make up for todays INFERIOR oils.
I reject the argument there has been a 'bad batch' of cams out there. The recent cam failures, I'm convinced, ARE 'oil related' for the most part, and in conjunction with improper breakin procedures.