Well the main difference between the traditional British hops and the American stuff is that the British hops are what is generally considered "earthy" while the American stuff is generally more "pine tree/grapefruit" if that makes any sense. I like both but they are different and you can pick out the difference easily. If you want to make an American style ale you generally want less malt contribution and more "over the top" (at least relative to British beers) hop flavor and aroma. For an APA I generally shoot for about 1.050 O.G. and then go for about a 40 IBU beer with alot of late/dry hopping. British beer has quite a bit of "nuance", in other words you can taste the malt contribution, bisquet/ caramel and maybe light toffee while American stuff is generally devoid of all that much in the way of malt flavors. As far as hopping goes, most British stuff has what I guess I would call moderate bittering and maybe just a bit of flavor hopping but not alot of late or dry hopping, at least when compared to the American stuff. Finally, most American ale yeast is very clean in relation to the British stuff so you generally don't see alot of "fruity action" in APA's.
Generally, both the east and west coast of this country have fairly soft water with the harder stuff in the middle (where I live). Those guys in the Pacific Northwest can cram all kinds of hops into their beers without getting harsh because the sulfate levels are very low. If you are using hard water you need to start being careful with the hops. My attitude is that any moron can make really bitter/hoppy beer, it's the artist that can make a bitter/hopped up beer that is enjoyable to drink. As far as Chinook goes, in my mind that stuff is about as subtle as Atilla the Hun. It has a very strong resiony/grapefruit/pine tree aroma and flavor and it covers everything else it touches. If you bitter with it and have any minerals in your water at all it can easily get very harsh. Now, to be fair Stone Brewing as made a fortune with that stuff but it's just not for me (and nobody died and made me King so what the hell do I know).
So, my suggestion would be to use say a 50/50 blend of good British pale ale grain and British lager grain (to try and cut down the malt character). Maybe a bit of medium crystal and a touch of wheat for head retention. Make a 1.050 beer and bitter to about 40IBU's. Load up on the late hops and maybe dry hop with an ounce or so for a 5 gallon batch. Bitter with Magnum or Warrior then use Amarillo, Simcoe, Cascade, Centenial or whatever "C" hops you can lay your hands on. Finally, try using that dry American ale yeast, I've had pretty good results with it and I'm a very serious snob (generally only use the liquid yeasts). You will end up with a pretty hoppy, dry ale which hopefully you like. Once you have made it once, keep good notes then start screwing around with it to your taste (sweeten it up, dry it out whatever floats your boat). Finally, I probably wouldn't bother "burtonizing" the water, most of the famous American pale ales are made with fairly soft water. Anyhow, have fun, good luck and it ain't my fault if you turn into a "hophead".
Drinking:Saison (in bottles), Belgian Dubbel (in bottles), Oud Bruin (in bottles), Olde Ale (in bottles),
Abbey Triple (in bottles), Munich Helles, Best Bitter (TT Landlord clone), English IPA
Conditioning: Traditional bock bier, CAP
Fermenting: Munich Dunkel
Next up: Bitter (London Pride like), ESB
So many beers to make, so little time (and cold storage space)
