Ant - a bit closer to home for you, I've always used Castrol GP50 (now Formula R) in my V8s. It's always maintained a stable pressure even at higher temps in my 460 Falcon, and it handled my dyno torture with my latest Cobra engine without a hiccup.
My engine guy over here was positive that he DIDN'T want a
synthetic oil with my solid roller lifters. He's experienced the case of too little friction with the synthetics - the roller just slides over the camshaft rather than rolling it's way over.
The supercharger guys were divided over whether
synthetic was any better, but it seems that no-one could agree.
In the end, I stuck with the tried and true Castrol mineral based product.