318, wrong rocker arms?
To identify right and left rocker arms look at the pushrod socket.
The left rocker arms socket is left of center, and the right is right from center.
On the right side of your engine the rockers even say LT=left\\RT=right.
Install the rockers on the left side of the engine the same way.
Get your self a new set of hold down bolts for your shafts.
You should not be using off the self bolts and washers for rocker shaft hold down bolts.
Get your self this book>>>> how to build small block mopar engines by larry shepard.
Basic information plus good performance info.
Everyone who owns a small block mopar engine should have a copy.