Those numbers are identical to the neighborhood I live and invest in.

If two identical properties next door to each other both sold on the same day, one for $500K and one for $600K, my county would later assess them both at the same tax value.

Is your rehab process identical to that of other flippers you know?

Also you would be violating the NJ Landlord Identity Law by not registering. 

(but not zoned for) Property is currently offered at 750k , a property right beside almost identical was sold for 725k on conventional mortgage and it was initially offered for 769k. (5.72% decreased on a conventional mortgage that took almost 4 weeks from pending to sold).So based on this data I have estimated(not exact science) that I could give a lowball cash offer for 550k(maybe w/ some luck) but with some room to go up to 635K (which is a 14% decrease on the listing price and hoping to close fast with a cash offer) 70% of $900k is only $630k, which would be the max you could refi. 

@Levi Davis We went through a nearly identical situation last year.

This plan does not avoid capital gains or keep his identity secret.

We don't flip here in California as out prop 13 penalizes people trading often we pay $15,000 less in property taxes as an identical building sold next door 5 months ago. all improvements are an expense at this point but appreciation has over $1,000 per day on just one property.

Essentially identical to a sale with owner financing but the deed stays with the seller.Yes, you can 1031 into such an arrangement as long as the contract has been written so that in the terms all of the burdens and benefits of ownership have transferred to you. 

The neighborhood has some identical 4-plexes on it that are currently renting between $600-$650.