[Formulajones]

The key words I took from the OP post was "low revving and 550hp"

That right there is going to be a hell of a lot easier with more cubes. So I'd be looking at 455+ to get that done.

Really doesn't matter what block it's based off of. It really boils down to what's available to you. Most of the time, finding a good 455 block these days is getting a little more difficult, so most go for the 400 stroker builds simply because 400 blocks are more plentiful and generally a little cheaper.