It depends on the result you want. Using the "2cfm/hp" rule of thumb you need about 10% more than the as-cast E Street/RPMs can do unless you want to run a very serious camshaft. One way or another air has to get in and out. If the heads can't flow enough fast enough, you either keep the valve open further and longer, or get a port that can flow what you need in the time you're giving it. The problem IMO is 470 isn't much more than a 440 in terms of how it acts. So a big cam will mean rougher idle, etc.
Can they make it? Yes.
Will you be able to run a shelf grind street roller or street/strip flat tappet cam to do so? Not in my opinion.
If it was me I'd look into a set of CNC RPMs and just sign on the dotted line.
Edit: Seeing IQ is doing the work - have him do the heads too...
