Here's one other thing to consider when using any electric water pump. They don't have a bypass like the stock water pump does, which means that the water won't be circulating in the block and heads until the thermostat opens up. Normally when the engine is cold water still circulates through the engine, by way of the stock bypass. If that doesn't happen, by the time the thermostat opens the water in the engine is very hot, and you will get a big temperature spike on the gauge as soon as the thermostat opens. It will cool down very quickly, but its still not a desirable situation.
There are two ways to skin this cat. First is, as previously suggested, drill and tap one of the adapters for a hole, but instead of using a single outlet, put a tee there. Run one side of the tee to the heater core, and the other side to the water pump bypass nipple coming out of the intake manifold, or in your case, the intake adapter. If you don't want to do that, you can also drill 3 or 4 1/8" holes in the periphery of the thermostat. This will let water pass by the thermostat even when it is closed, so that you will still have water circulation when the engine is running. Those holes will not affect the normal operation of the thermostat, and the engine should still come up to the thermostat's rated temperature. Just make sure that the holes are not covered up by the gasket when you install the thermostat.