a few YEARS ago, maybe 10 + years ago when i sold it. i had a 624 CI hemi road runner. after the cylinder wall cracked i had a 572 ci hemi built to replace it.
my friend built the motor. he built at least 10 600+ ci hemi motors.
my motor was a low compression budget motor with stage 5 heads with big valves and a bunch of used parts.
i think it had 500+ft lbs of torque at 1000 rpm. with low 3.23 gearing i could do 70 mph at 1800 RPM and i could still easily smoke the tires at will.

the biggest problem i had with it was the push rods kept burning up at the rocker arms pivots. big ci motors with large valves and fairly large cams require some spring pressure to work. the spring pressure along with running at low RPM causes this problem. it's a problem because the push rod / rocker arm pivot relies on splash oiling. at low RPM there isn't much oil splash. my friend solved the problem by using chevy type oil thru push rods where the oil goes thru the push rod to the pivot for oiling. once he did that we were good to go.