Oh yeah.... 500 rwhp is easy with boost. You can do it on pump gas, but you have to be willing to up it a little. If you're seriously considering the V10, just get a stroker 351 or 302 with forged internals, nice heads, and the right amount of boost (depending on the combo and displacement) with any decent turbo setup will get you there. I've heard of guys doing that with a junkyard Turbocoupe twin combination.
Chris