Does it need a roof and new heating system or just paint and flooring. 

houston is probably similar pricing to Columbus Ohio but way worse zoning laws. we take 20% on top as a GC and a guaranteed fee agreement. our contracted new construction projects recently:Single family new build spec home: 1513 square feet with 3 beds 2.5 baths 1 car attached $275000 approx $182 a square foot if calculated using heated square feet which means our cost is $145 a square foot. 3 unit / triplex new construction: 2008 square feet 2 bedrooms 1 bath per unit or total 6 bedrooms 3 bathrooms with 3 off street parking spaces. contracted build cost $395,000. no garage on this and better economies of scale with shared roof, slab, etc. $192 a square foot hard cost with our cost running approximately $157 a square foot. 

Just from my own experience, if you were not going to separate the heat, electrical, or plumbing, I would do it anyway. 

It's unique and you could make this feature an amazing centerpiece and hero photo.Since you’re installing a mini-split, heat isn’t the issue—it’s all about guest experience and aesthetics.

In court, I produced text messages between myself and the tenant showing I was attempting to fix the issue, but since she said she was without heat for 3 months during the winter, it looked really bad.

The garage was built to work on trucks having 14' ceilings and 2 bay doors heating cooling about 700 sqft.

While you may be willing to live without heat/ac or hot water for a week.

Let's say the AC or Heat goes out in 60 days, do you have funds to cover that?

In the winter the gas bill is a lot higher due to heating, but electric is lower.

Given the property is located in the Poconos and the property is vacant more regularly as an STR there are proactive measures  you should  be taking such as making sure there are heating sources so that the plumbing does not freeze and ensuring there are no blocks in the plumbing lines with routine checks.