I’m currently building a 400/470 with TF270’s up top. My build is a heavy car bracket race application. My theory on making the most of these heads was to open the valve as far as possible with moderate to short duration in order to take advantage of the flow capabilities while still building as much torque as possible to get a big car moving.
I called Howards and went through my goals and components and they agreed with my theory and spec’d one of their catalog cams that runs only 259/263 duration at .050, but with 1.6 rockers opens the valve to .680.
I’m still waiting on it, but I’m looking forward to the results.