I'd have put two AC/20s in, but I'm about 3 tons short because of that stupid "10 heatsinks" rule, even if you have a positive cooling efficiency with only 7 of them.
This might be more fun. http://mwo.smurfy-net.de/mechlab#i=140&l=b7f35916e7dc5434787833099e08b35da7fcf736