I don't think any of the HP, Magnum, 375 HP 440 where 10.0 to one except the 1970 440-6 pak 390 HP motors that had the advertised deck hieghts of +.005 above the decks, all the rest of the 375 HP 440 HP Magnums had around 9.2 to 1 compression ratio or lower from the factory due to combustion chamber sizes being way bigger than blueprint specs., same thing on the deck hieghts, way lower than blueprint specs. OP, that 262H cam is a known little bitty baby cam