If I can get him to lower 300 range plus holding the note at 6-7%, I can sell it as I won't refinance for at least 3 years, so he'll get the interest money but within 5 years so he'll eventually get paid in full. 

Value add to me are items that will actually raise rent or lower expenses that ultimately raise the NOI.- Reducing utility expenses through either separating meters or if you can’t, convert all fixtures to low flow.

We could have a downturn between then and now, which would force interest rates to drop back to today's level or lower.

@Lawrence RatliffFirst off I commend you for the hustle, the ambition, and the huevos (Spanish for eggs referring to something else) to start your RE pursuits.but ...1) I agree strongly with @Justin R.2) I am not a big fan of any of the so called "rules" but the one that I use as a quick guide on ROI calculations is the 50% rule for lower cost units. 

If you got the property lower, then you may have an easier time to find a buyer.

This way you get to keep what I’m assuming is a lower interest rate.

The money that people try to save by not using a Realtor typically results in longer days on market and a lower selling price.

How much lower rate do you think you can get on a 15 year loan?

Once you retire, your lower income and write-offs from rentals should reduce the taxes you pay on the 457. 

I would also consider the route of not house hacking if your current rent/mortgage is less than what you can get out of rent from the lower unit.