@Colin M. Like Tyler, I am a local Realtor®/Investor. I'm happy to help in any way to evaluate deals you are looking at. I am well connected to all the top wholesalers too if you are a cash buyer. If not, I can help locate other areas that may interest you. If Kissimmee/Polk County is what you are looking for, there are plenty of multi-family units in that area. This market is always lacking in mulit-family inventory and when they do come up, they go super quick.
As far as evaluating, I like to start with 40% of revenues go to expenses (vacancies, utilities, lawn, pest, taxes, insurance, management (always include this even if you self manage!!) as well as advertising etc. That leaves 60% for profit and debt service. The 1% rule you asked about is typically that you want the rent to equal 1% of the total purchase price. So in your case 1% of $315,000...you would want to collect $3150.00 per month in rent. Have you checked Zillow, Rentometer etc for rent analysis in that area, $1300/door sounds low for a 3.2. If you are interested in short term rentals, your money will go a lot further in that area. you could get a SFR and generate $50k+/yr and have a place to come on vacation!
Hope this helps, feel free to reach out if I can help in any way. Good Luck.