Is the Walbro 255 pump still the go-to OEM replacement for turbo builds? Is there a better alternative for something making ~450whp? IIRC, it didn't seem to fit as well as it was a bit smaller in diameter.
~450WHP is pushing the limits of the Walbro 255HP pump, but it is certainly still the go-to for most normal-power turbo builds. It fits just fine assuming you get the kit for our chassis.
For a bit more flow you might start looking into an in-line Bosch 044 pump... That's the one I like for when the Walbro is not enough.