That depends on what exact advice you are currently seeking. If you still want someone well-versed in Tolkien's Silmarillion, you might have a tough time, as I certainly have not read it, nor am I immediately able to name someone here who has.
Now that doesn't mean they don't exist. I’d be willing to bet you dimes-to-dollars we have at least
a few folks here who have read it, but just how much you expect of them might be a deciding factor in whether or not they choose to accept your request.
However, if you are just looking for some story-related critique and opinions, I might recommend you try the TTG, perhaps with someone specific requested in your comments. I can recommend morning_angles if you want some grammatical nitpicking. He’s not always a breakneck-paced reviewer at times, but he’s got some good insight. Casca also does fairly well, and I could likely certainly swing away if you need it real badly (Though alas, I am but a mere mook). There can be some good reviewers to choose from in there, if you look through them and do a bit of homework to find a name you really want. If you ask for someone specifically, word should get to them pretty quick (We like just hanging around as much, if not more, than reviewing at times). You’d hopefully hear back on whether or not they will accept your request in a reasonably timely manner.
You can also try asking Roger, though I'm not quite certain if he'll accept and I can't appear to find his specific review thread. Don’t know if he hasn’t made one here yet, or if it’s just gone. Still, might be worth it to ask him. The worst he can say is “I’m not really interested.” At best, he’ll either accept himself or redirect you to someone much more likely to say “yes”.
I’d have recommended Nick to you as well, but I think he’s a little preoccupied with personal issues according to his thread, and will probably not be able to get around to you at this time. You could still ask, but I imagine the answer will either be a “I can get around to it eventually” (which might be a while, depending on the exact nature of whatever he must take care of first) or just “I can’t.”
Lastly, if what you’re looking for is just general advice, I suppose you could always ask around on places like the TTG, or look for our reviewer soundslikeponies (though I c