I am OK with this however finding the building (searching for the last year) has been difficult. 

How difficult is it to fund a 80/20 or 70/30 split for financing.

Both of us on loan, we get owner occupied interest rates and flexible down payment amount (although I feel I would want to put down 20% to remove PMI)Once Dad sells his home (easier to do than finding a duplex) he will give me about $55-65k of the profits, be the owner occupier in a duplex, go halfsies on repair/cap ex, but only wants to pay about $500 per month (he'll adjust for inflation!) 

It entails the following steps:Calculate the Net Operating IncomeDetermine the appropriate Capitalization Rate (or ask your broker)Divide the Net Operating Income by the Cap Rate to arrive at an estimated valueWhile the steps are simple, the underwriting is a bit more complex.

And that some will disagree with as well."1% rule" = monthly rent should be at least 1% of acquisition costs; for some, acquisition costs include all purchase related costs PLUS any repairs / improvements needed immediately upon purchase."2% rule" = monthly rent should be at least 2% of acquisition costs; this rule applies more so for lower rent amounts, roughly $500 (and lower), and can be difficult to meet this rule at higher rent amounts.

Assuming all the numbers are accurate (NOI, Cap Rate etc.)

Many novice investors seem to see the cap rate as only ROI and forget how it directly correlates to risk.

@Ciara Coleman It definitely makes sense that it would be difficult to move around a lot with work and a young son.

She said she would be extremely difficult to find  a new place in the next 26 days with the weekend. 

There are some local job workers including school teachers, 6 or so Sect 8s, 3 retirees and 3 'absentee' renters.  2nd home folks who like the area and have family there but have houses and lives hours away.The vacancy rate when I bought my 1st apt bldg there in '03 was 20% and I was buying at a 14 cap.