Tax strategies for an equity portfolio that is >90% long term gains?

TL;DR: inherited extremely appreciated assets that don’t qualify for step up in basis. Over 90% of portfolio is long term cap gains ($371k of gains on a $400k portfolio) and portfolio allocations are wack (no tech exposure). What should I consider?

My severely special needs uncle passed away earlier this year. Several family members had left him money to make sure he never was wanting, but with low expenses, his two trusts mostly sat and grew. My aunts / uncles decided to disclaim a portion of their inheritance to us nieces and nephews. It was very generous of them.

Some of the assets were not available for a step up in basis because they already stepped up when my great grandmother left her assets to my uncle. My aunts / uncles allocated all the capital gains to the disclaimed portion and kept the rest.

I don’t love the portfolio as it lacks diversification, has no tech exposure, is morally dubious, and has underperformed bench marks. I’d much rather own S&P 500. Same time, I’m not sure with extreme tax bill how to go about rebalancing, and if it’s worth it. The portfolio is: JP Morgan, coke, Disney, shell, chevron, Boeing, Raytheon, McDonald’s, Union Pacific, Otis, Colgate, Berkshire, and ATT. Several positions have been held since the 80s. I don’t fault any of these investments, just wouldn’t have personally bought any of these companies.

Can I transfer any equities to my retirement accounts?

Is it better to do a multi year rebalance to spread gains out or rip the bandaid and do it in one go?

Any resources I should review?

Thank you!