Trust - Dumping Higj Fee Advisor, Moving to Index Funds or Fidelity Managed Account

Hello,

I am the successor trustee of an inherited trust, with assets currently invested with and advisor at an obscenely high fee. I have terminated the advisor, and am moving all assets to fidelity to minimize fees. The previous advisor had a majority of the funds invested in an account that appears to mimic the SP500, but with common stock.

There are ~$700,000 in unrealized gains in this account. All stocks transferred in kind, so I’m left with a portfolio of ~200 stocks. I’d like to simplify this into a few ETF’s.

Fidelity mentioned that they have a managed account that will also mimic the SP500, but with significantly less fees than the previous advisor. They also claim to do tax loss harvesting. My main concern is that they will have to readjust the current balance of stocks by selling some off to fit.

I know at some point there will be a tax hit when I sell. My questions:

-Am I better off selling everything now (in a way to minimize short term capital gains taxes), and moving them into ETFs?
-Or should I consider the fidelity managed fund, take advantage of tax loss harvesting, and pay yearly fees?

Thanks!