Not a lot (I don't remember the specific amount). It was a copy, not Moore's original complete with locks of his hair stuck in the stapling or whatnot. :-) But it's definitely Moore's work, judging other script/proposal samples I've seen online, and has, as I noted, his signature sense of humour.
Here, I'll give you a sample, from my favourite TKJ panel:
Now for this final flashback panel, we continue to close in implacably on the young man from the rear so that now we only see his half figure or less. He has turned suddenly to face us, still clutching his head in mental pain and horror. His lips are split into a wide and bloody grin. The eyes sparkle with a hideously deranged light that has travelled beyond reason or recall, and the hair that he runs his fingers frantically through is wet and green and slimey. He laughs uncontrollably and hysterically, and the 'HA HA HA' sound effects fill up the entire background of the panel, oppressively large, with the Joker standing in frong of them, clutching his head and screaming with laughter. No trace of the young man remains. There's only the Joker.
Copies do pop up on eBay from time to time, if you're interested. Alternatively, the first twelve pages are viewable at Four Colour Heroes</em>.