Jerry
I have been running/building dry sumped setups since 1972---I have never seen or heard of a tank draining into the engine to find its own level---if it were to do that--it would have to pass thru the
oil pump( highly unlikely) pass thru the lines to filters/coolers ( again unlikely with only a few inches of head pressure) and then have to go thru the engines
oil galleys/bearings,Etc.
On Can-Am cars and some Formula Atlantic and some of the newer GT cars you have to pay attention to your route of the hose so the oil doesn't leak out of the tank thru the pump and into the motor..... it has happened.......
If the system is blowing oil out the top of the tank, the breather/separater system/method is inadequet
All of the guy's running in Nascar and SCCA on road race tracks find the level of their Dry Sump tanks ...it is common and is different on each car...... depending on the tank and type of car and tracks it's going to run on ...... Your comment on inadequet breathing is wrong.....
With a current tech dry sump pump a vacume pump is unnessary as it is possible to pull over 20 Hg with the lobe type scavage pumps and 10-12 hg with the old tech gear pump
Not all pumps will pull a vacuum especially in FE motors ....we have tested 3 different types and they will not pull a vacuum in a FE motor..... or I should say they won't pull enough vacuum to do anything.....
Breathing or Venting of the large motors has turned out to be the best way to go......and we have over 4.5"inches of breathing on our motors..... and they make very good HP....
Morris