I have the same setup under a 90 gallon. mag 9.5 return pump CSS 125, used two acrylic tanks 20x15x15 just small enough to fit through doors. At first I had two 1" bulkheads connecting fuge to sump, was not enough flow. Used 1 1/2" pve elec. conduit fittings and gasket material for bulkheads, save over 30 bucks on bulkheads.
My problem has been getting rid of the micro bubbles, If I were you I would try different baffles. At first I had way to much flow through skimmer area, microbubbles were flying through baffles. tried adding bubbletraps on the sump intake/skimmer output. filter floss between baffles worked, but pain in the azz to maintain.
Now I have increased the flow to the fuge and microbubbles are coming from the other way. where fuge dumps into the sump, used 2" pvc to make tailpieces to contain the microbubbles, they blew right through it. So threww in some pieces of LR which slowed the bubbles down. I have it down now to a few bubbles getting through. just enough to be a nuisance., thinking of adding more LR between baffles and making an acrylic box to go around return pump, limit the access for the bubbles. here's a couple of pics
maybe spacing the baffles further apart may help? mine are 1" apart .
wish I had the answers , i'm a newbie, hope this helps