420-435 crank HP stock depending on the year.
400-410 with cold air kit, cat deletes and tune
435-445 with Cobra Jet Intake and mono blade throttle body.
470-480 with Comp Cams & full length headers.
Add E85 and you can add 5-10 hp to those numbers.
You see some dyno higher and some lower. But typically those big hp number cars seem to never make it to the track or run well when they do. So take dyno numbers with a grain of salt, as I am sure you do, John.
That being said, I have heard Rich Groh Racing making a lot of power with these motors. He has had some really good luck with porting these heads and testing different cams. These heads flow just shy of 300 cfm stock. I know a few years ago RGR stage 3 heads were just over 340 cfm. And who knows what he has come up with since then. When you have a motor capable of flowing so well I guess you can make some big power. Just imagine what a RGR 320+ cube, high compression, race motor could make.
JPC is also very well know for getting the most out of a combo. This car could have a lightweight flywheel & clutch assembly, aluminum driveshaft, and so on. And revised driveline angles that help get more power to the tire. That is why they have been record-setters in many classes. Including Coyote Stock.