[AdamIsAdam]

What about doing one of the aftermarket water pumps like:
http://www.summitracing.com/parts/bra-1649

or

http://www.summitracing.com/parts/mil-16281

Would that alleviate the need to modify the clearance and eliminate human error?

Since I'm not looking for originality, what is the downside to going with one of these (aside from price)?

I like slapping shiny new parts on my car. It's fun, especially if they work well.