@Jason Boritz  We just recently finished an ADU in La Puente, CA.

I'm a GC, and I know MY basic rates (been at it for 18 years), but venturing out into the financials of an entire build start to finish are a new realm to me.  

In 2017, he pulled the permit with drawings,, but didnt finish the permit process due to an illness, and unfortunately passed away before the permit was cleared; consequently the permit expired..

(holding off until we finished the minor reno work!)

He finished 40% of the job and is not responding to any phone calls or messages.

I would listen to the BP Podcast with Thach Nguyen on how he knocked on one hundred doors a day , five days a week for ten years and that got him one million USD per year from that ACTIVITY.Make sure you dont miss the part where he says one home seller let loose a dog on him and he had to get attention at the hospital from the bite.I would also pay attention to the Tom Hopkins Champion formula to embrace rejection on pages 110-125 in his book Mastering the Art of the Sale.Especially the part where he says , you are paid for each rejection you getThen TAKE ACTION, make the calls, follow up leads, ask for referrals, make offers, buy properties, choose your exit strategy etcin making calls i would attempt to incorporate "negative phrasing" as taught by Steve Trang, to locate buyers, sellers, private money lenders.I would also set a saving rate as taught by Anthony Robbins from book Money, master the game, becoming of an investor, taking advantage of the power of compounding I would also keep in mind the 10000hour rule from Malcom Gladwell's book, Outliers reminding myself that attaining world class takes commitment

By adding better finishes, he thought the house would command a higher value.

Additionally, you absolutely should finish the ADU if possible whether you move into it or not.

I'm not sure how inflated this is but it seems as though I already have about $100k in equity into the house, which is crazy..The neighborhood is about 80% finished but still under development and they are starting phase 2. 

Current value of 2:1/2:1 duplex is $550k.If we just add 2 bedrooms and 1 bathroom by finishing the basement, the total rental income of $5000/month.