So if you have any additional gain left over after taking the 121 exclusion, including the depreciation recapture, you can shelter the rest in a 1031 exchange.

If someone were to buy their shares, they would gain ownership of 2/3 of the business.

Quote from @Jamie Parker:I got a photo with Tom Cummings, Prolly the only real value I gained with 7-8k invested in education that year.

I myself attended local meetups when I was starting and gained insights about their experience on local market

It is a good group of like minded investors and I think the value you would gain there would be very beneficial as you get started. 

My first thought was sell to lock in your tax free cap gain.

This approach allows you to present professionally and gain valuable insight into the process, which you can then replicate in-house for your next property.

He self-manages, is his own handyman and had to pull out the little equity he gained to pay for roofs and HVAC. 

Even if things don’t go perfectly, you’ll gain valuable experience that will help you with your next project.

Well, if the FMV of the house is at or near $300k based on reasonable comps, and there's no legitimate benefit to the client's offer (i.e. all cash, fast closing, no contingency, whatever), I'd probably quit working with them because there's really little to gain working with cheapskates and bums who just want to steal other people's property.