Are there restrictions to interior and exterior renovations?

Full Property Address is:1160 13th Street N Birmingham, AL 35204Current Listing Price: $185,000Number of Units:22 of which 8 are occupiedCurrent Day Rents at 08/22 Units = 36% Occupancy:(196*08=$1565 per month / $18,780 a year)Valuation at 36% Occupancy:$84,000 - $92,500 ( I would offer this price today since this would be based on the current rents which are abysmal probably due to a landlord who doesn't know how to market and to rent out to the region $200 rents are way below market rates) (Analysis in excel sheet - link below)Prospective Rents at 100% Occupancy:(500*22=$11,000 per month / $132,000 a year)(600*22=$13,200 per month / $158,400 a year)Valuation at 100% Occupancy:$1,215,000 - $1,225,000 (Analysis is in excel sheet link below)Projected Repairs: I currently don't know since I don't have pictures of the interior, but I've factored about $75K ($3500 per unit) for repairs since I don't know the condition of the interior.

You may own the sheet rock on the walls, interior pipes & electrical, Kitchen cabinets, bathroom fixtures, etc.

For example say one of the units is livable, while the requires some interior work in order to be rentable. 

One property I had there is some special texture stucco and interior plaster from the 60s, I hired two plasterers, and fired both before I found Andrew. 

The other Realtor seems a bit more questionable, but on occasion especially with multifamily properties coordinating with tenants for interior inspections before the seller has an accepted offer can be difficult.

The interior is going fine and we added new siding to the exterior.

My father and I did about 95% of the interior work but hired someone to handle the exterior work including painting.

The units were recently updated and refreshed with new interior and exterior paint and new flooring. 

Interior is bland / old, but not in terrible shape....but would certainly need to be updated (floors / paint / counters / bathrooms, etc.) if you are looking to get top dollar.Long story short....has anyone ever done anything like this before?