Check your oil level, your timing and your mixture. Adjust the timing a little or richen the mixture a little if necessary, and keep your foot out of it until the cam breaks in. Pull the plugs and turn the engine by hand to see if you have anything dragging or tight. A brand new rebuild will run a little hotter than it will once it's broken in, but 225 is too hot. Also, your coolant mixture should not boil over at that temp if you are mixing 50/50 antifreeze and water.