Where can I find stock Android for Samsung Galaxy Note 2?
A great place to start would be on the ROM list for your device on XDA.
There are many options available, so which one you want to install comes down to user preference.
Please note that it will be required that you root your device, so proceed with caution as your warranty will be void.
Your other alternative is building it yourself from source.
Also, if you like Lollipop, i suggest you use Nameless Rom.
this Custom rom (Nameless) availabe on XDA :
Download Link :
http://sourceforge.net/projects/namelessrom/files/n-2.0/n7100/ the best and faster Rom for now for Galaxy Note 2.
also for Stock Rom :