So that is def a consideration here as well. 

Is this a price i should take into consideration when negotiating?

@Ritch Bonisa thank you for the input, that's true I didnt put the codes into consideration, the house been empty for 5 plus years, who knows what's not in code, plus applying permit time around the area is a pain also, it could delay rehab time and increase holding costs. 

Another consideration is that if you are barely cash flowing on a home in an expensive market and you aren't taking into account capital expenditures, the first time you have a major maintenance repair (new roof, major plumbing or electrical issue, etc.) you will be in the negative for years to come.

All contracts, options, or other devices not based upon a substantial consideration, or that are otherwise employed to permit an unlicensed person to sell, lease, or let real estate, the beneficial title to which has not, in good faith, passed to such party for a substantial consideration, are hereby declared void and ineffective in all cases, suits, or proceedings had or taken under this chapter; however, this section shall not apply to irrevocable gifts, to unconditional contracts to purchase, or to options based upon a substantial consideration actually paid and not subject to any agreements to return or right of return reserved.That appears to close the loophole. 

Also at my current day job, I make an about 35k per year so I'm hoping that the banks will take into consideration the potential rental income of the property when making a decision.

What considerations should I have with an 8-plex that differ from single family?

Take nothing off their rent, there is no reason to.You are unfortunately diminishing the potential buyer pool considerably by having a tenant in a SFH.

@William Fisher probably want to have an attorney draw up the application and rental agreement to make sure you are not breaking any law.

That is no different than drawing on the HELOC you own, and depositing that into the business.