Looks like your numbers are going to work out nicely...
1.5 X 350 (skimmer)= 525...and 10X in fuge(28)= 280...so 280 + 525= 805...which is right where your overflow and return are (should be)..
Boy, did you luck out...
Not to dig up an old post (ok well to dig up an old post) I am going to do this... I knew it could be done and it's the perfect application for what I am trying to do!!!