When to draft Justin Upton in a keeper?

[drunkmonkey]

I'm in a 10-team keeper league, and we keep 8 players each year. We're finishing up the 6th round of the draft, and I'm wondering when is too soon to take Justin Upton? If he's going to develop into the player people are predicting, he could be a first round pick in a couple years. Should I take him in the 7th (if available), and plan on keeping him a while? Or hold off?

My team so far:

C - Victor Martinez
1B- Mark Teixeira
2B- Brandon Phillips
3B- Aramis Ramirez
SS -
OF- Adam Dunn
OF- Josh Hamilton
OF- Matt Kemp
OF- Alex Rios
UT-

SP - John Lackey
SP - Roy Oswalt
RP - Carlos Marmol
RP - Matt Capps
P - Josh Beckett
P - Carlos Zambrano
P -

[Yoda]

Now.