So I've been reading a book and in the book it says that a healthy grown female should weigh 40-45 pounds and a male should be 50-55 pounds. When I was speaking to a friend today who has owned a few as pets she says that her males weighed around 78 pounds? So how much do these little brutes normally weigh?

I think 45 pound.

The book is accurate. English bulldogs can easily become overweight, due to their aversion to exercise. It's harder to tell when they're overweight because their body type is so different from most other dogs. 50-55 lbs for a male is optimal.

Various books and articles (I wanted one before I decided to rescue a mutt)

Depends, not all Bulldogs are the same height. So a taller dog should weigh more, their vet would tell them if their dog is overweight.

45 lbs.