Right so when you're 73 you'll need to start making RMDs from your 401K/IRA. The benefit of the Roth Conversion is to grow the money with tax free withdrawals, and it's not subject to those RMDs. So you're paying tax this year to avoid paying tax in future years, at some future projected tax rate. Based on your total retirement account balance you can figure out what your RMD schedule will look like, and also consider tax on social security which is triggered for certain income levels. How much and how fast to convert to Roth depends what that overall picture looks like.
This article from Fidelity may be helpful
https://www.fidelity.com/viewpoints/wealth-management/insights/roth-ira-conversion
Also a note above I think your deduction will be higher by $1950 for over 65 than I used above; and the new additional 6k deduction from the 'big bill' phases out for AGIs between 75k and 150k.
https://www.hrblock.com/tax-center/irs/tax-law-and-policy/one-big-beautiful-bill-senior-tax-deductio...
I don't think I can help further on this - I was trying to answer your original question on the tax implications of a large Roth Conversion and whether it's a good year to do it, and make sure you're not surprised by the jump in LTCG tax. Hopefully this has given you some points to consider when discussing further with your advisors.
