Daniel, I am doing the same trim and baseboard in my house. Just extend (notch) the lower cap and the shoe halfway onto the door casing. (about 1 3/4" for a 3 1/2" wide casing) You could angle the cut slightly or in keeping with the style cut it at 90 degrees. This is similar to how the plate rail is finished.
How do I terminate the base trim (specifically the shoe) when it base trim stops at a door casing? Should all base trim pieces stop at the same edge of the door side casing or should some or all extend past (notched) somehow?
How to Install Craftsman Trim
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