oil drains, oil pressures near sump

[bricktron]

the upper oil pan, at least mine, has two ports for oil drains. one is the turbo drain tube that sits in a fancy gasket and has profile and an O-ring way up at top. the other is a nipple for the crankcase oil return which i have a rubber cap clamped onto. since i'm attempting to recreate the turbo oil drain with a flexible line (transmission hose or similar), it would be more convenient to use the plain nipple.

does the fact that the two nipples are at different heights indicate that the level of pooled sump oil reaches the lower port and not the upper? if my rubber cap disintegrates the short nipple would spew out oil? how do people reliably block these ports off if needed?

cutaway for reference: