Which is the better oil for a D1 V8 - synthetic or mineral based?

From what I've read synthetics work great in modern engines, but they all have roller cam followers these days or curved face lever followers. But in old fashion pushrod V8 engines like the Rover V8 you can expect accelerated cam and lifter wear with synthetic oils.

Flat faced followers/lifters in these old design engines need zddp (a zinc phosphate - Zinc Dialkyl Dithio Phosphate) additive in the oil to prevent wear. Synthetics (and many modern mineral oils too) have precious little or none as it poisons cat converters.

I don't think that many synthetics have a high level of ZDDP because modern CATs don't like it.

Oils that do have higher levels of zddp are generally ones with an SG rating or lower. Like Valvoline VR1, Castrol Edge 25W/50, K-Mart KMX, etc

The thing is not just any old 20-50w will do, it has to be one with a high content of zddp.