Am I going to throw a belt doing this?

IF it is aligned and IF the water pump and crank both have the same groove diameters, you should be OK

If it does seem "long" you might consider constructing an idler on that long side to pull it in towards the center

Thanks they're both from CVF and they basically line up perfect.

The belt is too long but I was just using it as a prop to show the issue I had going on.