They need to be able to trade equal or up in value to satisfy their 1031 Exchange reinvestment requirement. 

If I want to convert this sizeable space into 1 or 2 apartments, is there a tool or rule-of-thumb to use to estimate the costs of this project?

There is also a tool here on BP to find HML in your area.

Do you have any tools or strategies to help you do that? 

This is a great forum with very knowledgeable members that will help to guide you in the right direction.The site has quite a few tools that can be helpful for new members.

I'll have a bit more money that I can then use to invest in other properties; hence being able to utilize all the tools BP pro has to offer.

I'm going to do some research on the what if or wayfinder tools, but the answer seems to be "time".

I took a class from Robert Kiyosaki in 2013 (before YouTube, BP, etc) and it was immensely helpful to start to understand the mindset and basic tools and understanding that goes into RE Investing. 

Use the network tool up top here and start connecting with local agents in Chicago.

If you are unfamiliar with Investway, it is a great tool to run your own comps and not have to wait on agent comps.