Everyone would be Genin at 4th level. Oh, in case I forgot to mention;
I'm going to do a Part 1/Part 2 sort of thing, like the series itself did. Part 1 will be a quick little prologue of sorts. Just to establish things and to start at a fairly low level to warm everyone up. So the PCs should all be roughly 13 years at that point. Not going to touch anything even remotely sexual there, for obvious reasons.
The Part 2 will be 3 years later, and then everyone will be Level 8 and eligible for Chuunin status.
Ok, also I was thinking use advanced human template then if possible. Reduce me into level 1 char to present the well made breeding background for Mibu clan. So sure, I do not have the raw experience and talent but perhaps my char is rising genius star and so have high expectations from superiors.
Aha, I forgot about that. Ironic, considering I once made an Advanced Human Mibu character as well once.
Fair warning, losing a level can hurt pretty bad in Naruto D20. Particularly at low levels, where you're restricted to low-end techniques.
And the Mibu bloodline doesn't particularly get useful until you get to about mid-level. This Campaign might end up going on that long (I hope!) so it might be worth the payout in the end.
In the Part II thing, he'd be Level 5 with a total bonus of +4 Str, +2 Dex, +4 Con, +2 Cha while everyone else would be Level 8 (unless they also have a bloodline or somesuch)
Supposing the game got to level 20 or something crazy like that, you'd have to spend 2 bloodline levels, take the ECL 2 from True Red Eyes and the ECL 1 from Advanced Human. In short... Level 15.
That's a pretty big disadvantage, so I'd recommend you make the most out of the increased ability scores... which would likely be seen most obviously in Taijutsu Save DCs and the bigger chakra pool. Meaning you could afford to use high-end taijutsu techniques and they'll often pay off. Unfortunately... you'll lag behind everyone in levels so it'll be difficult to learn those strong high-rank techniques.
Also... So far I have 4 people interested. The idea was to have a 3-man team but I can be flexible.