Personally, I think the stroke on the 543" makes the block a time bomb. The 505" would be much easier on the block. I guy a know loves those 505's. Built and raced several weekly. All are still together. He doesn't swing any larger crank as he still uses stock blocks.
But if it's spinning less rpm & getting the same results as a 505 with the same csa in the heads shouldn't they equal out ? I'm pretty sure I wouldn't want to spin a 4.5 stroke at the same speed a 4.150 stroke.
Torque peak should be 4680 rpm with mw port 543 ci & 5150 for a 505.
Piston speed is better in a 505