there are some difference between the 400 and 440 decision that are not applicable to picking the 361 over the 400.

400 is a smaller package than the 440, making it easier to fit.
400 has the largest bore diameter of the B/RB's making breathing easier.
Then there is the difference between rod lengths to take into account.

http://victorylibrary.com/mopar/rod-tech-c.htm

The only reasons to use the 361 is because you have no other choice or you just really want to.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.