Rest assured 20W50 will have substantially more pressure than 10W30. Why would anyone set bearings loose??? especially on a high performance engine. I imagine your mains are .002-.003" KC knows how to build engines.
Its a double edge sword, sure if you are going to race for 60 minutes straight and run your
oil temp up 20W50 might not be to heavy. If you start and run around town 10W30 is the answer. Heavier
oil just overflows instead of penetrates. You can wear your engine out with 20W50 with day to day starting.