Have phase 1 architecture drawings/site plan that have been informally reviewed/okayed by local building inspector.

If you ever need any local architecture / permit advice send me a message. 

Let's say you'll be at $120/ft to build so you're at ~$257k in build costs not counting another ~$10k in architecture and engineering.

The list you have there, assuming the work was completed professionally (architectural shingles, good quality kitchen) and barring destructive tenants (which seems not to be the case) sounds like he put about $70K in already.  

The general character, look and feel, etc. will most likely remain low-income for the immediate future just due to the architecture, layout and demographics. $350k is a decent price for a duplex anywhere in Boulder County, it’s a very entry-level price point.

I do real estate because I have a passion for housing and the art of architecture.

Some of the differences with SFR that make them less valuable than otherwise similar comps are location on a busy street, smaller lot, bad condition, structural defects, higher tax area, different school zones, different deed restrictions, access to main roads, rush hour traffic, obsolete or unpopular architectural style, inferior finishes, time since remodeling, age of roof, flooring, and others too numerous to mention.To get the discount to fit your formula, you’d probably need to find a house needing significantly more than $15k of work.

.#3 Contact Local Contractors for Labor PricingCall local Subcontractors and get budget pricing for common repairs on your typical rehab project.For example, call a roofer and ask what their average cost per Square of Architectural Asphalt Shingle Roofing would be on a 1,500 sf house, with a 6/12 pitch.Note: Some contractors will be reluctant to share pricing without seeing the property, but tell them you are just looking for a rough budget number you can use on future projects.#4 Compile Your Prices into a Spreadsheet or Estimating SoftwareOnce you start to get a better understanding of Labor and Material costs you will want to store this data into a spreadsheet or software that you can use to help you streamline the estimating process.The Book on Estimating Rehab Costs comes with a spreadsheet that you can use to help you populate your own database of labor pricing and material pricing.

Any permitted work must come with Architectural plans even for lite interior permits.

It is on the National Register of Historic places and the prices there have been through the roof for at least 5 years. it is comprised of wonderful brick Revised-Tudor homes with whimsical architecture and is a truly lovely place.