With $600k, you could just not touch it and then be free to do whatever job you want to just cover living expenses with no thought of retirement I'm pretty sure. "Coast FIRE" achieved. EDIT: By "not touch it" I meant invest it in something safe and easy and then you'll have full retirement money in 30y
Suppose you retire at 65 and live to 90. That's 25 years. $600k is $24k/year for 25 years. Of course your investment may grow in the meantime; but there will also be inflation. I would suggest that $600k is insufficient savings for a retirement that would support the lifestyle you are accustomed to.
You need an investment that at least matches inflation, and is large enough to cover fixed living + increasing medical costs.