Some feedback, I brewed this beer for my 180th batch of beer a couple weeks back. I had Zombie Dust in the past, so went from memory, but I was able to drive through and get some real Zombie Dust to compare against.
I followed the recipe as written, I mashed VERY LOW because my experience with WY 1968 London ESB strain is it leaves malt behind, so you want a dry beer. I mashed 148-149F and it's exactly what I wanted for the finish in the beer.
Overall - the hop and malt flavors are very very close to the real deal. Brew this and you will be happy.
If you want to geek-out, please read below. If you want a good beer and don't want to nit-pick this recipe against the real thing, stop reading and brew it as is written!
Geek notes / BJCP National Level Judge Comments:
My original assumption about the recipe was correct; this clone is a bit darker than the real beer. 1.0lb of medium dark-ish specialty grain (20 SRM Melanodin, Crystal 60) is going to give you a deep gold beer, with amber hints, usually.
Even with the color, the beer is still pretty close in flavor. If you are wanting to get an exact clone, reduce the Crystal 60 to a 1/4 pound addition. Continue to mash this beer low and ferment with the WY 1968 strain.