Under high torsonal loads the crank tries to twist itself into an 'S' so you will tend to see the highest wear on the #3 because #2 and #4 main are constantly trying to see-saw between eachother.

You said you're running a cast steel crank so yours safest bet for longevity might be to cam it where the motor doesn't want to rev that high, if the heads can't pump up there the bottom end friction will start to act like a rev limiter.

The other thing is on the street your tires are the safety fuse, you're not really dead loading the motor because you'll break traction before you'll ever twist anything to failure.

I have a 427 ford windsor (4.04" bore and 4.17" stroke with 340 rods) in my cobra replica and that is a torque monster, rarely sees over 5800-6000 but in a 2400 pound car it doesn't need to. I pretty much build all my SB strokers (except my Rocky that spins 6800-7000) that way.