Exactly. It's about Spring Pressure. The anti-wear packages in many current grades are as good or better than what was normally sold in 1968 or 71. However if your running a cam with fast ramp and high spring pressures then yes you probably want to be sure the oil has the a really good package for the sliding follower action.

If you really want to know about oil selection for older engines, then check out Richard Widman's paper. He even sent out a sample of classic motor oil for analysis.
http://www.widman.biz/Corvair/English/Links/Oil.html