The thing to consider with the stock pumps is the impeller. There are two types, cast and stamped. The better of the two is the cast. The best thing for overheating issues is to get the clearance between the impeller and divider plate as close as possible.
I've done just about everything to get my convertible to run cooler. All but the side masticated fillers and divider clearance. For me that's one project on the books when it gets warmer.
