More than likely, you will be out the time, the court costs, any lawyer expense and come away with at best a judgement that will costs you more money to collect.The best route is to talk to the GC and if you cant find common ground, part ways and find one that will in fact finish the work. 

With local home and land prices so expensive, I'd like to explore building a Tri or FourPlex on the back half of the lot. 

It will be more expensive for sure.There are some places you can get some deals on things delivered but they are often not the best quality.

We got it for a really good price of $360,000 on a super low interest rate (3%) back in '21.

ctype=...Meanwhile my 100k house I bought in cash 17 years ago sold for 325k but net only 237k after selling expenses, renovation and taxes.

It’s in California and the tax basis is quite low.  

At first they looked cheaper when I was checking them out, but then I realized they were actually MUCH more expensive than my current brokerage. 

We aim for a target cap rate, say 6%, aligning with our investment strategy.Here's an example: if a property yields $1.2 million in income and costs $10 million, resulting in a 6% cap rate.Then there's the adjusted going-in cap, factoring in potential changes in income or expenses.

In my market, which has been fairly stable with a 3-5% appreciation rate over the last 20+ years, a house that was bought over 10 years ago will normally have enough equity for me to be able to buy it at a low enough price to wholesale it.

I value this part of the partnership pretty low because I can always go to a great GC I know and hire him to remove this from the equation.