I think you need to get your lens farther from the negative. Have you tried mounting your 80mm lens on the 135 cone? That may work or it could be too far away. You may need a cone about half as deep. I can get everything from 35mm to 4X5 out of my fixed condenser D-2, but it takes a bit of imagination. On a flat board, I have to use a 75mm lens for 35mm negs. You could probable come close to getting an 8X8 print using your 135mm lens. Maybe 10X10 if the column is high enough. I'll put a square neg in mine tomorrow and see what I get.