You are going to hurt yourself with those heads, they're good to 7500rpm easily and you're going to kill port velocity as well as shroud the chamber. Sound good still?
The 4" bore is NOT NEARLY large enough to support those heads. They're basically modern tunnel ports. Think of a boss 302... good at 7500rpm, lame from idle to 3500 (where you drive most of the time, right?).
Unless the vehicle is a weekend warrior or dedicated drag vehicle, stick with cleaning up the 317s on there currently. They'll allow for around 275-300cfm @ 0.550" lift... that's huge AND still retain massive port velocity. Also, you'll then have no install issues.
