I tried a Meziere water neck that's listed as working for an RB engine. They don't tell you that you have to mill it if you're using a stock type water pump. After calling and finding out to mill it and use a chevy thermostat, I got it milled and then went to put it on to find out that the thermostat is the same size as the water pump outlet. I was not pleased.
I'm using a MP 90 degree water neck with no trouble at all.
