In 79, they had a L48 and a L82. You have the numbers mixed up.
No way to tell if that is a block from either without you looking at the stamp pad and looking up the suffix. Could be a truck or van motor.
It is located near the front of the passenger side valve cover. It will look like this (the suffix ie.CMR will tell you what block it is. Use a wet cloth not sandpaper to clean it if not visible):
Post what you find here. Someone will decode it for you. And just because the vin or title says one thing it does not mean the block was not changed. Good luck.