You're better off looking for Alligator dogs, as Gary is probably the most successful breeder of that line, so most Alligator dogs today come from Hammonds' Dogs.
However, I'm having quite a bit of trouble finding it pure. Usually it's crossed with Chinaman or Patrick blood.
If I'm not mistaken, Tom Garner has a couple of Alligator/Chinaman crosses. Plenty of people hate on TG and call him a peddler, but the man has produced some awesome bulldogs. They're pretty friggin expensive though.
Sadly, most of the people I know of who run Alligator or Hammonds stuff are overseas. If you're willing to import, Limey Kennels has some very nice Alligator/Patrick crosses.
Sirius Kennels has some very nice Alligator dogs, sometimes crossed with Chinaman.
Game Kennel - European Home of the Alligator/Rufus Family
has some very nice Alligator dogs, both pure and crossed.
The vast majority of Alligator blood that I could find is located overseas. I'm sure there's some of it over here, I just wasn't able to find it.
I know this isn't really what you asked for, but it's the best I could find lol