take the pulley off dude. tell your mechanic that if he's so interested he can run it on his engine.
Why even chance it for a week or two at the start? you'll be running the engine in / mapping, so won't be able to see it's full effects / gains or whatever it's meant to do, then if you open it up to test it, you're running the risk of the above failure.
I wouldn't even run it up with that pulley installed dude. Not worth the risk.
One of the main reasons I joined the forum was for the experience and advice of other like minded enthusiasts and there are a lot of knowledgeable people saying change that pulley, or it is at your own peril! Your choice buddy, but i'd already have my toolbox out!