oil accumulator

If you are going to drag race or track race with the car, then it may be a good idea., but a well designed oil pan is essential. If it is a street car - not needed.
However, you do need to prime the system before starting after a rebuild. The Hemi oil pump doesn't seem to prime very well.

Did you read this link in the "Sticky Threads"???
How do you prime the oil pump?