Search strategies for finding a non-techincal co-founder?

I'm a solo technical founder working on a new startup. The product is fairly technical so after doing a bit of product-market testing I've been heads-down on it for the past month or so.

I know right away the area I need the most help with is the business side of things -- marketing, sales, market research, etc. But being a professional software engineer for 10+ years, the vast majority of my professional network consists of other engineers.

How do you go about searching for a biz-savvy partner? And what criteria do you use to evaluate them? I assume there's no Github or other such site for business folks.