I have a sb400 with pretty much the same upgrades as you. I'm also running cast heads.
My machine shop told me I'd be pushing around 580 Torque at least...
From what you said your truck dynoed at I am going to be very very very let down after I spent 6 grand on my engine if it performs the same way....
Not a bad number but 300ftlbs is a long ways from 580ftlbs that's for sure....
