The incidence of valve train failure may be more common when parts (camshaft/lifters) are replaced. A cam that has been broken in properly and in the engine for many years may be just fine and using modern oils in it may not create a problem. I think it really depends on that, and how the car is driven as well. If you like to drive it like a performance car, RPM and heat increases the demand on any engine and the components where there is extreme pressure created in a very small area. The ZDDP critical to the survival of those parts has been engineered out of modern oils (and diesel oils) for many years now, so Rotella may not be as good as it once was. Diesel engines have different needs than gas engines. Diesels are low RPM motors, and they contaminate the oil much faster. The anti foaming/detergent additive package in diesel oils is much different than oil for gasoline engines. Something else I learned in researching this is that the calcium detergents and ZDDP fight each other in an engine. ZDDP wants to stick to engine parts, detergents try to clean it off. That is why additives may not be as effective as intended depending on the oil they are used in. There was a good thread on this on V8buick years ago. Worth reading,
I think anyone rebuilding an engine with new cam and lifters should be concerned with using modern oils. My current engine uses a roller cam and lifters and roller rockers. I still use Joe Gibbs hot rod oil as that is what my engine builder recommended. I have been using this oil for 6 years now. my car gets driven hard on the street, and I have about 30 11 second passes down the 1/4 mile. So far, so good.
They also make a specific break in oil, BR-30. I think it is relatively cheap insurance.
1970 GS455 Stage1 Race weight 4025 lbs.
TSP 470, 602 HP, 589 TQ
MT headers, Gear Vendors Overdrive
Best E.T. 11.54 Best MPH, 116.06
1998 Riviera SC3800