Thank you kindly for your response.
As an update, I gave her a spinal without any problems (single pass, 27G Sprotte needle) and a superb block.
Unfortunately, she developed what seemed like a dural puncture headache on day 2. It was mild enough for her to function, but was clearly postural. It went away with conservative measures on about day 4. I'm very glad I did not have to perform a blood patch on her!