For example I came across 4187 N.

@Roy N. - Sorry, should've been more clear!

But you also have the n=1 statistical challenge.  

Where I have a questions now is that I have a potential 'investor' who might be interested investing in buy-n-hold properties with me by either; 1) lending me the down payment portion from their SDIRA at a set interest rate and term which I would use to take out a portfolio loan (20% down).

However, for buy n hold instant equity is tough to pass up and 80% of ARV is pretty good. 

Yea we tried an fha last year got into a promising contract (we were using a IDA to fund the closing and part of the down payment) on a short sale n a big bank decided to throw in one last request (to the sellers) at closing and they wouldn't budge with the seller on it so the seller got up and walked.

Let try n make this work

Investors hopefully are somewhat smart in their purchase and an investor considered it a good purchase; one they expect to make money on.If the cash flow is about the same or better than the duplex then you are likely near the top of your area on cash flow.Note that if you have $40K instant equity but the duplex cash flows a few hundred more each month then the duplex with no instant equity will be the better long-term buy n hold.If the purchase shows to be a good investment they you need to figure out the way to finance it. 

Hello @Tim Wang and welcome to BP and the N Austin area. 

@Thomas S@Roy N.