Car getting real hot....

Well the engine was removed changed cam the heads were redone asking with that the crank was changed only things used were the pistons add the engine had been rebuilt original a few yrs earlier but had really low mileage (less than 3,000 miles) after having a problem with a lifter dropping I decided to take the engine out and redo it the way I wanted to, lime I said different cam, heads, lifters, valves etc.. The only part that remained the same were the pistons and the induction,
The car never went above 160 before that's why I was thinking, maybe the water pump went ?
Thanks.
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