Spend down inheritance or spend 401k money first to minimize taxes and maximize legacy?

57M, \~1.5 mil in 401k, about to receive inheritance of \~400k.

Planning to expatfire in 18-24 months to a LCOL area. Living expenses expected to be under $60k USD/year (36k core + 24k discretionary).

Will delay drawing SS for a few years so that I can do some Roth conversions. Benefit at FRA would be \~$4000/month in today's dollars, but don't know when I'd pull the trigger.

Given the LCOL, I anticipate that I will leave a fairly large legacy, it occurs to me that it might be a good idea to keep the inheritance in a brokerage account so that it can eventually be passed on with a step-up in basis. This would be in addition to the Roth account.

Meanwhile, I could spend down my 401k to minimize future taxes on RMD's. I'm thinking to pull enough out to fill the 22% bracket and convert anything above living expenses to Roth. Looks like that would be around 35-40k converted each year, after taxes. I would only pull money out of the brokerage account to avoid going into the 24% bracket or to avoid the SS tax torpedo (not sure if this is even possible).

Is this a reasonable plan? Am I missing something?