I'm just starting out as a DIY weekend wrencher. I have two classics--a 1980 C10 SBC 350 w/cat. converter (mine) and a 1979 Trans Am w/Olds 403 w/cat. (wife's). I've read up on oils with high ZDDP for flat-tappet cams and the supposed problems they cause for cat. converters. So far, I've found no products on the market for this situation. That said, I've also read that broken-in cams do just fine with modern oils.
If you're in this situation too, what do you do? If you're otherwise an expert on the topic, what would you recommend?