dos the turbo assembly have to be mounted horizontally? What I'd like to do in order to simplify plumbing is to mount it vertically. Basically, from the top down it would be exhaust housing, turbine housing, the compressor housing on bottom with the air inlet pointed at the ground. I planned on using a scavenge pump since there wouldn't be a gravity effect for returning the oil to the pan, but will I have any other oiling problems? Will the pressure form the oil pump be enough to keep the bearing lubed?

(BTW, this is actually for my GN, so I have a TON of room in front of the motor to work with, I'm just trying to simplify plumbing. the original turbo was on top of the intake manifold and was horribly inefficient)

 

Nope. The turbo seals are not designed to have the oil sitting on top of them. You need to mount it so the oil inlet is on top, and the drain is on the bottom, as close to straight up and down as possible.
Only reason you would need to run a scavenge pump is if you mount it down low and it won't gravity drain.

Any other mounting is a recipe for early seal failure and instant smoke show.