Thor's full name was always Thor Odinson wasn't it, and the Hammer does say
"Whosoever holds this hammer, if he be worthy, shall possess the power of Thor."
So it's not much of a stretch having a girl that looks like Thor with the power of Thor to be called Thor, and the real Thor dropping his first name since obviously he's not worthy to posses the Power of Thor so why use the name. I've not read the title for while, do they actually call her Thor to her face or does she have a normal name? and oes anyone in the Marvel universe call her Ther like they do on the internet?
Anyway back on subject, while I don't want to do a Thor, I'm thinking about doing a female beta ray bill, maybe use a horse skull as a basis for a head and go from there