I know it's your thing but man I really don't like that scanline treatment.
I've been following your project on tumblr tho, looking super amazing - coincidently watched a youtube video comparing all the ports of the original Robocop game last night too, needless to say, yours is looking miles away from any of the official ports.
One scene that really impressed me in the arcade version (as I'd only played the ST version previously where it's omitted), is how they showed the edge of the buildings here:
. (Guess you can't do that exactly with the angle you've gone for and not making suggestions, just something I thought looked cool!)