Looking to get involved in building a small residential portfolio to eventually combine in an aggregate sale for one small apartment building.

This is strange because a property is rarely equally good for both.If you can flip and make $40k or buy and hold and clear $4k a year in profit then it is clearly a flip. 

The market can definitely fall lower than 20% but it is pretty rare. 

If you combined it into your mortgage. 

If you don't have enough Solo 401k funds to purchase the property as an all-cash deal, you can combine your Solo 401k funds with non-recourse debt to purchase the investment property.

@Jacob SampsonRight now the rent is $1575 combined. 

This is rarely achieved in the note investing arena, and may be well worth the additional risk, depending on your financial situation, your real estate knowledge and experience, and your risk tolerance.This sounds like something I would have definitely done at 27, would have probably done at 47, and most definitely won’t do at 67 LOL.

From the 1031 perspective though there is one other possibility that may not naturally occur to you.If you can combine those sales in a compressed time frame it would be possible to combine them (the time frames have to overlap) into one or more larger assets. 

It will be rare to find one that has not been contacted already.

Rarely have I had a tenant this late not fall behind and dig a hole they can’t get out of.