I'm with pyze-guy. Get some shorter bolts. They don't cost much.
I run a singleator on the RegularBike. It makes a little noise, not a lot. You can run it with either a pull-down or a push-up spring. Try both to see which is quieter for you.
Right now, I've got the pull-down spring installed. I'm going to swap out my rear cog for something smaller though. When I do, I'll switch the spring. With the push up spring, the chain engages more teeth on the cog.
And yeah, have fun. Building my single-speed was a great project.
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Religion is a good thing for good people and a bad thing for bad people. --H. Richard Niebuhr