Ok so i just stoved KK vs a calling range for villain and it came out;

Text results appended to pokerstove.txt

144 games 0.000 secs 28,800 games/sec

Board: 7c 6c 3s 7d As
Dead:

equity win tie pots won pots tied
Hand 0: 25.000% 25.00% 00.00% 36 0.00 { QQ-TT, AKs, AKo }
Hand 1: 75.000% 75.00% 00.00% 108 0.00 { KK }

So it looks like i missed out on some serious value on river seems to be a clear bet/fold for value now.