If you are dead set on blocking off your EGT NOW, just make a piece of 1/4" aluminum cut to the same size as that flange, or the EGR gasket if you still have one, then only drill out the holes that the bolts go into. A simple procedure with a dremel tool and a drill. A piece of aluminum should be easily attained from a welding shop or similar. Seal it with ultra copper (high temp) RTV and never look back.
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