I realize most people aren't going to read through 28 pages of replies, so I will just restate a few things about the recipe. People seem to blindly use the same amount of bittering hops. DONT!!
The IBUs are listed in the recipe as 30ish. If 0.75oz gives you 40, then why not adjust it? I did a partial boil (4 gal?), so obviously I got worse utilization than one would get with a full boil.
Also, bittering variety isn't important as long as you are using a clean bittering hop. The beer is too roasty to ever notice a difference between Northern Brewer and Magnum, for example.
Yes, other English and American yeast can work. Will it be exactly the same? Probably not, but it should be close.
If your chocolate malt or roasted barley is a little darker or lighter, that's fine. No need to make quantity adjustments. It's going to be black either way.
Instead of amber extract, can you just use all light extract and increase the amount of crystal malt? Yes.
Are maltodextrin and lactose interchangeable? No. If you want to try using it instead of lactose, go for it. Just realize you won't be brewing this beer.
I wish I could edit the OP, but I can't.
Cheers!