Sorry not to be able to help find pins, but would point out that you may not need them.
EDIT: Very sorry, missed the 'pivot' part...serious brain fart...
Note the following:
1) The width of the internal cavity of the fire control pocket of the AR-15/M-16 family of rifle receivers is standardized. This means the pins will have the same engagement length whether aluminum or carbon fiber is used for the lower receiver material.
2) The trigger pin is retained by one of the legs of the hammer spring dropping into the groove closest to the end of the pin - pin is forced to remain centered and is not going anywhere.
3) The hammer pin is retained by the spring-clip embedded in the hammer engaging the center groove - pin is forced to remain centered and is not going anywhere.
The only issue caused by the thicker carbon fiber receiver walls vs standard length pins is that the pins don't flush up on the exterior, which is purely cosmetic and have no effect on function. Theoretically, the shorter pin engagement could wear sooner on the carbon fiber receiver, but would probably take a gazillion rounds to loosen up.
Good luck finding longer pins if you really feel they are needed, but I've never seen them.