Rolan Kraps: As you know, I ran into the same problem with the Cylinder & Slide fixed rear sight on my 627 UDR. The front sight was too tall to work with it.
I replaced my C&S with a Bowen "Rough Country" adjustable rear sight. Similar in design to your SDM, it is fully adjustable and has a square notch that works well with ramp-type front sights.
