Me personally? No. I run the aforementioned Swepco 15w40 in my 2004 Silverado with a 5.3 vortex, and I've used 40 and 50 weight oils for a long time. However, there are lots of 10w30 hdeos out there that would also do well in a SBC. Rotella T5 is one of them, since you are already familiar with their products. It's available in 10w30 and 15w40. People tend to think 15w40 is thick, it's really not. Again, my opinion, but 15w40 is the best overall performing oil viscosity.
I hope I'm not making you overthink things. SBC engines run fine on just about anything that vaguely resembles motor oil. I'm just a little selective about the Lubricants I use.