1981 360 questions / differences

The engine has the same mounting as the earlier engines, the newer engines are a thin wall light weight casting and shouldn't be over bored more than .030 according to mopar, otherwise they are the same. The light weight castings started in 1977 and were used up to 1992, then the magnum engine came out. It should fit where the 318 is now but you'll have to change the drivers side motor mount as it will be different, or make a spacer to bolt it up.