Cam for a stock 383

I recently bought a 68 Dart GTS 383. the car is all stock and I am thinking about putting a larger cam into it. Does anyone have any ideas as to what would be the largest or best cam that I could go with? 727 trans, 2800 stall, 3:23 gears, stock intake & exhaust, 906 heads. I was thinking about a MP 509, but I am concerned that it will kill the low end.