They're designed run inverted and in 99.9% of all applications thats they way you'll find them.
It isn't a problem if you know what you're doing, which you obviously don't. No critisism intend. It just doesn't sound like you are ready for this yet.
Adding a pump is just going to completely confuse you and you'll just become one of the names that hangs around the engines forums asking strange questions because you've completely out of your depth.
You must get together with some local talent that has real experience running engines/flying competitively.
He'll help you out.