Call section 8 and find out the details yourself.  

Have bought hundreds of property at auctions, including the first property I bought (detailed in Bigger Pockets Podcast #82) and the very first thing is you have to know value. 

It can cause some extra documentation needs, but as long as your income has been stable or increasing over the last two years then we should be able to make the argument to make it happen. 

PM's will use the portal to provide you with up to date communication, monthly and annual accounting, tax reporting and detailed annual reports. 

Everything aforementioned is great information, I just wanted to provide a little extra color in the hopes it assists your client's decision.

Share some details! 

So there are a few ways to look at this, the 1st question is are you sure your renovation’s will double the property value, most renovations on primary residences, your lucky to get 60-70% of the dollar cost back out upon sale, so really nail down your comps, than you have basically a math problem if your rate on your primary goes up how long if ever before that extra payment is more than 400k in taxes, that’s just a simple calculation to help you decide, but I suspect you actually have a different question here, from a purely financial perspective my guess is the best option is to do anything to avoid that tax hit, but one of the reasons to make money is to spend it on things that you enjoy, based on your overall financial picture and a subjective view of how much enjoyment you will get out of a renovated home, you should decide if you want to roll your profit into another deal or “cash-out” your winnings, I love cars and I’m willing to spend more than is fiscally smart on them because they bring me joy, there is nothing wrong with that, but i don’t think it’s a fiscally smart choice, without knowing your exact property id imagine a renovation would fall into that category, so that’s the terms I would use to decide.

If I get him 500k extra he said he will do it.

Here's a bit more in detail about how rates are calculated for DSCR loans:1.

Would you have been able to sell the car better and for more had you kept it in your garage and detailed it?