318 build problems & new direction

Do you have large tube headers and a high flow intake? I've found honesty in the dyno programs will produce a more accurate number

No I don't. I assume that would be 1-7/8" tubes? I actually have Dakota manifolds. When I select those, I lose a lot of hp, like over 40. But most people run headers, so I just base lined it with headers for reference, and then know that I am leaving plenty of power on the table.