>>71233 (OP)it might.
Psychedelics heighten blood pressure by constricting your blood vessels
normally you offset this by drinking enough water or taking magnesium supplements, but if you dont you can suffer an ischemic stroke.
At older ages it might cause a heart attack by closing up the coronary artery, since those get weaker with age.
At any rate I doubt your plan will work, psilocybin can only be converted to psylocin if your gut has low pH and is basically empty, otherwise the conversion is done way too inefficiently.
On an empty stomach 5 grams is enough, but if you've had even just breakfast you might need far more.
If you dont tell her she will likely just eat something and lessen the effect.
Secondly, remember the pH thing? If she doesnt eat limes or something similarly sour beforehand she'll just barf the shrooms out.
For these reasons I think LSD is the superior choice.