Sorry to hear about your issues, Rob.
Personally, I use Joe Gibb's Driven 10w-30 conventional motor oil in my 340 Dart with a Comp Cams high energy 274 cam and it has been good for 2 years now since I've owned it.
And the car runs pretty hot in the summer with a slight drop in oil pressure when it's hot and about 210 degrees.
The cold oil pressure is stable at about 70 p.s.i. upon start up and goes to about 60 when warmed up, and about 50 when really hot.
I did not build the engine, I bought it this way.
I chose Driven because it has the right amount of zddp in it for our older engines, and that's what was recommended to me by the builder.
It was broken in with Lucas break in oil if that matters, and then changed to Driven after about 400 miles.
The engine has about 1,500 miles on it now, and is really good (other than the heating issue) and has good power.
I only put about 1,000 miles on it in a year, and I change it every year.
Also, I use a Wix 151515 filter if that makes a difference...