I would basically agree with what Monte is saying, unless there is a desired/targeted hp level you're after, that could easily be reached with the lesser cost/easier option.
If you're trying to make the most power you can, then buy the highest power potential heads you can afford.

On my bench an SR CNC 295 flows basically the same as a 440-1 CNC 325.
When the 325 can really out power an SR is when the displacement vs port volume starts to become the limiting factor rather than the flow(like on a 572 for example).

For a super class 499, if I had CNC ported MW size SR's, I'd just keep using them until I was looking to make a big move in power........ at which point you'll have to start thinking about a real block.