We have a lot of experience on that one and can help.
Many of our big-block customers think they need heavy oil for those engines and it simply isn't true--today's engines are typically built with tight enough clearances that you can run 30wt (remember, in a 5W30 or 10W30 multigrade application, it's the "30" that's your operating temperature, truly the weight you'll run at...).
Rotella is a great oil in gas engines for break-in, but not beyond that. It's filled with additives specific to diesel fuel dillution and operation. Regardless, a way to bring down that oil pressure is simply to move down one grade in viscosity, to a 5W30 or a 10W30.
Please remember that there is no such thing as Red Line "straight weight". We offer a 30WT Racing Oil with far less detergency (gives you more lubricity, but you have to change it far too often for a street application), but it is a 10W30 multi-grade and says so on the bottle. The 30WT name can lead guys to the wrong point, but that's the way racers judge the weight--at which they will race at.
One last thing about the ZDDP mention--both the Red Line racing oil (orange labels) and motor oil for the street (blue labels) have what the general public is calling ZDDP, but what is really a complex and expensive antiwear additive package. API rated oil (like Mobil 1, Royal Purple, and all the synthetics and conventional oils at your auto parts store) do not have the antiwear you guys are looking for. Red Line products exceed the API spec and include that antiwear you need.
We still have the Red Line Chevelle that you likely read about for years in PHR and appreciate you guys. Hope this helped....
Red Line Oil