460's have both, front and rear sump, depending on application. Almost every boat application I've seen so far was with a front sump, to the engine, pan though. (Oil pumps in the front as well, with the dizzy, lol).
Problems I have HEARD MENTION of, mostly from Mike Kaase's school of thought is, breakage of pickups or housings on oil pumps using rear sump and Boat pans, (Such as a Milodon marine, canton or the various others out there). Kaase makes a special pump et al to "fix" this.
I've never seen it happen, or heard of it actually happening, in my short time with the 460, but mine with the rear located pickup and Milodon pan has been fine thus far.
Ray