If your squish is .048" it is already a little on the high side for a 250.  Adding a thicker gasket will make your squish clearance too wide making the engine more apt to having detonation problems even when you are running 110 octane fuel. 

210 PSI on a 250 is a little high but not that high if everything else is spot on with the 110 fuel.

Low compression does not eliminate detonation when the squish clearance are excessive