Can anyone tell me how to figure power needed for a electric stunt. Watts to weight?

Last time I looked (which was a while ago) it was 7W/oz average (use for setting battery size), 11W/oz peak (use for choosing motor and ESC).

Like Mark said it's more complicated than that -- even putting aside the fact that a timer with an accelerometer in it will cause you to use more power, you still need to choose the right motor kV, prop size, pitch, etc.  And, no matter what you do, all the math will just get you in the ballpark anyway, insuring that you'll have a first flight that leaves you feeling that you can make things better.  You'll still have to fuss and fiddle to get everything matched up to your airframe and style of flying.

Thanks very much! That"s kind of what I was thinking but, wasn't sure how close it needed to be to rc. I scratched my on design profile with nobler moments that should be really close to 42oz with a 54" wing

There should be a lot of planes of similar size listed in "List your Setup".  Go, look, shamelessly copy.