After a darkroom fire, the first replacement enlarger available was a 60-year-old DeJUR 4x5 condenser model. To use it with 35mm I had to improvise a 3.5 inch tall chimney to fit between the bottom 4x5 condenser and a 35mm film carrier. It works well enough to still be in use, almost 20 years later. It's been decades since I've used an Omega 4x5, and don't know if this shortcut works on the Omega. If it does, the chimney should be about an inch shorter.