440 should be better platform. As mentioned you can get a little more compresion out of it by shaving the heads some and using a steel shim gasket. FWIW my old coronet had a maybe 9:1 (more like 8.8:1) 440, stock 906's Summit 488 cam, RPM intake, 750DP, el-cheapo headers and 3.91's car ran 12.90 all day long in good weather. 13.0's in the heat. Nothing fancy.