ls 4.8 with a carburetor
 

What cam should I run stock engine

Way to many variables there, you need to have some goals here.

Do you want it to drive nice?
Do you want it to idle good or be choppy and not be easy to tune even with a carb?
Do you want to run a stall converter or is this a stick shift car?

At the very least you will have to upgrade valve springs.