If the truck does not have all the necessary CA smog factory installed you will need to drive the truck 7,500 miles and wait two years so that it will classified as used.
If the truck does have all the necessary CA smog factory installed you will need a weight cert., an odometer cert., a smog cert., a Application for CA title, the out of state title, a CA DMV employee will need to fill out a vehicle verification, and you will need a boat load of cash to cover sales tax (based off of the dealers bill of sale).
Probable too late but I would make the out of state dealer make CA registration part of the sales agreement.
First thing CA DMV will look for is the factory sticker that states CA legal or 50 state legal.