I'm aware that the purchase price needs to be the same or higher than the house I'm selling to defer 100% of the gain.2.

I am of the firm belief that you can make reasonable money on multi-family in any area so long as you buy right and aren't in a super rough area of a city/town.The Laws in Illinois can definitely be strict towards Landlords, but so long as you have a solid PM who doesn't defer your property's maintenance and is willing to shoot straight with you when problems arise as well as does things by the book, you won't have serious problems in that regard.

Since you said it’s a fixer upper with deferred maintenance, I’m curious if you plan to renovate yourself or contract it out?

I borrowed from my Deferred Compensation plan through my job. ( retirement) How did you add value to the deal?

Then consider any deferred maintenance that has been well deferred and make adjustments accordingly. 

We're now in the process of re-positioning the property by renovating units and taking care of deferred maintenance. 

There seems to be a lot of deferred maintenance from just driving by and not doing to much of a in depth look. 

It is up-to your employer to write it into the 401K plan policy.There are downsides to taking a loan against your 401k such as the portion that you loan against doesn't grow tax-deferred free(technically it does a little since you'll likely paying yourself around 1% as interest to your 401K)

Solo 401k investments build your retirement portfolio and grow tax-deferred or tax-free.

What is the deferred maintenance?