If you are unsure of what constitutes legal notice in CA, consult an attorney, because if your notice is legally insufficient, and you have to file an eviction on that notice, the court could dismiss the eviction based on the legally insufficient notice.

Gave us written acceptance, went through the appraisal process, but then while rounding 3 base, choked.

We set the price based on our original assumptions but the offers we received were all well below what we needed. 

As per county records, land value was $190k and structure value was $474k, total value being $664k.

Your search right now sounds like it can be swayed based on data, but you need knowledge.

Which site is the most accurate to estimate the fair value of the house based on your experience? 

Given land appreciation in an area like this, is this a deal you would pursue?

I bought a vacant commercial piece of land about a year ago- (seller finance- $100k down/ $200k balance due in Dec 2024.

And based on your statement "the more we thought about it, the more we realized we do not have the risk tolerance to rent out the illegal basement unit and would rather make it legal" it doesn't sound like it's a good fit for you.

Building new sounds great, but it's usually way more expensive per square foot when you factor in land, materials, labor, and permits.