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