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...I am a big fan of used stuff in my bicycling. I have, in the past, made some decisions to reuse stuff that was less than optimal. (For example, I used patched tubes from the co-op for a number of years, carrying a spare tube in case something went wrong.) I finally got tired of fixing stuff on the road (even though there's a real sense of satisfaction in pulling off another roadside repair. So in my case, I would not reinstall that crank. There are a lot of deals on cranks right now, as stated by an earlier poster. And so long as you get the threading and the shell width right, you ought to be fine ordering one online. You can go with that 175 length, or switch to 170 or 172.5 (some other common arm lengths). If it's a road bike, the shell is most likely 68mm wide. If you want to calculate (and change) your gearing, you can order one with different tooth counts for the chain wheels. But if you do that you might need to change the chain length a little bit.
It's pretty hard to go wrong