Need help trying to figure this out..

[gentlearts]

I agree with the other posters..you're making this much too hard. Roast it at 325 for about 20 mins per pound, basting with butter every 30 minutes or so...no liquid, no cover on it. Let rest for 15 mins or so before you carve it.
It wouldn't hurt to test your oven temperature in case its not correct.

[spiderbear]

I do mine at that high of a temp and have no problem with it. Makes it super juicy. I'd flip it just once, and rely on a meat thermometer stuck in the thickest part of the thigh to tell you when it's done. Start breast side down, always.

[brook2ga]

I roast mine (same size) at 425 for 90 minutes and it comes out perfect every time.