I'm afraid I can't offer much. One article I found says for Cyclobenzaprine
lethal dose is 338 and 425 mg/kg in mice and rats, respectively. This would amount to over 18,000 mg for a human weighing 120 pounds.
As for the other,
Although the lethal dosage of gabapentin is not yet known, researchers found that people who consumed 49 grams of Gabapentin experienced unpleasant symptoms.
According to an FDA study, 8,000 milligrams per kilogram (mg/kg) of gabapentin did not harm mice. However, the mice experienced acute toxicity with drooping eyelids and labored breathing symptom
As is, doesn't sound like you have enough. Of course alcohol would amplify the effects, but I'm guessing not enough to matter.