I have spun rod bearings in higher reving 340s w/ a HV pump and stock 4 qt pan with no baffles. I believe that was all due to oil control, or lack there of. Usually # 5 rod bearing for what ever reason. I have picked up 3 340s w that same # 5 spun.
Milodon said that the small block oil pan has a very short rear sump wall. That allows oil to spill backwards out of the sump pickup under hard acceleration. Chrysler did this because the rear of the pan needed to be lower to clear the oil pump. Solution is to lower the sump down or make a cutout in the middle of the pan to increase the rear sump wall height. Also to install shelf or dam at the rear of the sump.
Here's the cutout in the middle with the rear section stock height to clear the oil pump.