Hey Rob,
1st: Took you a year?!
2nd: Mag 9 is over-kill!
You'll need to do what Jason did... he built a box on the back of the tank where he put a durso stand pipe inside there. The bulkhead just transfers the water from the overflow to the durso box.
I wish I had pics of my setup. I have a 12" routerd slot in the back of my acrylic tank that waterfalls into a 15"x15"x5" box behind the tank... and in there I have a 1-1/2" durso standpipe in there. I have a Velocity T-3 at full throttle and can't hear a thing. Its perfect because it surface skims but I don't see and overflow box or anything... its like "magic"
I would of loved to do the same thing with a glass tank but it just wasn't feasable so I sold my glass 120g to a Canreef buddy. I remember seeing Sanjay Joshi do this same thing on his 180g
glass tank but he got it done at a sandblasting place... but even I'm not gonna go THAT hardcore.
The idea we talked about gave you low profile, wall to wall overflow on a glass tank. Same kinda thing?
You just gotta modify the idea a bit but should work great!
Good start.