Why use a passenger side water pump housing?

Good morning,

As I assemble my plan for a strip 440 in my '67 Barracuda, I was reading up on the vast array of water pump housings and have seen a lot of mention of the passenger side lower radiator hose hook up. Is this for clearance issues? Radiator selection?

Seems like there has been a lot of chatter regarding heating issues with the passenger side hook up, but that might have been because of the 440source casting issues.

Anyway, just confused why people are running it.

Thanks.