Gary I’d say -10 is overkill for 450whp, but knowing you i’m guessing you’re planning to go higher than that in the future. 
Good data Matt. You can see that the Denso 310 pump gives you a touch more headroom than a wally 255, but only up to 22 psi. I’d switch up from a single Walbro or Denso 310lph around 500-550 hp. You can run twins or switch to an external above that. Again these are just guidelines and they depend on your setup. If you’re NA, you can go further than FI guys on the same pump due to BSFC and fuel pressure. Those running high boost require more pump capacity than those running low boost. Remember that as I mentioned above, fuel pump flow decreases as fuel pressure increases.
One nice thing about the Denso (for some people) is that it’s quiet. Many of you know that Walbros are a bit noisy. Also the Denso is OEM quality and they’re known to generally last longer than Walbros. However, they cost nearly 3 times as much, so most people stick with the Walbro.
As JnJ mentioned in the other thread, if you go to a big external pump, a pump controller is key to avoid fuel overheating and pump damage, especially for a street driven car which isn’t always at or near maximum effort. If you’re running twin Walbros or Densos, some engine management systems allow you to automatically kick on the secondary pump when certain conditions are met. For instance I’ve tuned cars which kicked the secondary pump on above a certain manifold pressure. This serves a similar purpose as the pump controller by pumping less fuel when it’s not needed. This decreases flow through the return system and excess recirculation.
-Mike