What HP a Basic 408 stroker

Most ported factory castings simply can't move enough air to make big numbers on a 4" arm. If you're already at 375-ish you have room to improve if your heads were ported. Your heads should be flowing somewhere above 220-230 depending on the work and your HP is low for that much airflow. So something's off. "quite a bit of work" doesnt always mean big performance.