You know it is kind of funny, That scoop at the end of the fretboard on your 8 string is slightly modified from my "bat wing" scoop at the end of the fretboard for my concept of WarriorofMetal's 7 string "Dragon Rider". I took the scoop idea from CanuckBrian's 8 string. So unintentionally you modified it from what I modified it to, to what it was originally, and they are both 8 strings. Odd, funny, ironic, synonym...
And caught up in my rant..... I forgot to say anything of your mock up. It looks great, i think that scoop in the fretboard really works for the design. A good counter-point (forgive the pun) to the lower point. Hard shape to match the headstock with but the one you have on there doesn't look as out of place as I thought it would.