I just got the water pump and water neck off of my 235, and the build up inside the block seems to be a lot. I was wondering if there is a way to flush the block before I put it back together, and before it runs?

the old water pump had one threaded inlet on it for heater, and the new one I got from NAPA has two threaded inlets and the main outlet for the radiator, Do I just plug one of the holes or should there be one that looks the same as the one I took off?

I also was given a 12v coil at NAPA, will this be okay to run on the 6v system?

That's me in the back of my bolt on the home page