Leupold QRW Low’s will not clear a Leupold 40mm objective bell on the SBL rail. QRW Mediums will give about 1/16” of clearance, QRW highs will offer 3/16” clearance. On standard 1895’s, low rings will typically clear the hammer, but require the rear sight to be removed or at least folded, so I often end up using mediums anyway. BUT YOUR SBL IS DIFFERENT. My wife runs an SBL with a Leupold VX3i 4.5-14x50mm, either high’s or extra highs. I forget. But the specs on a 40mm Leupold say you’ll need Mediums or Highs in their quick release. That doesn’t tell me whether your rear sight ring will clear the tube or objective bell though, I’ll have to measure the rear sight height to be sure how much room she needs...
Marlin 1895’s REALLY require a cheek riser to work for scopes. I need one even for the irons (not much height between my cheekbones and eye). Victor Company make a very inexpensive plastic saddle which screws to the top of the comb, but admittedly, I typically use a cheap Allen elastic shell holder over a bit of foam rubber, or a Hornady branded stock pack with foam rubber shims underneath so I don’t put screw holes into my levergun combs.
