Rough numbers you seem good to go. Great job building up the savings and having no or little debt. Run some of the retirement calculators like Firecalc or Fidelity Retirement Planner, to see the numbers. Reminder that doing the Roth conversions, you will need to get additional money out of the cash account to pay the taxes on the conversions. You can't use the 401k money to pay taxes without the 10% early withdrawal penalty. So that may be approx 15-20% of your Roth conversion amount you will need additional withdrawal from the cash account for fed and state (if applicable, assume you live on CA?) taxes.
You can also set up a 72t withdrawal from your 401k if you want to tap a little of that money before age 59.5, maybe that's a good way to pay the taxes on Roth conversions? The 72t let's you get money out without the 10% early withdrawal penalty. Only drawback is you have to take SEPP (substantially equal periodic payments) and do it for 5 years or until 59.5, which ever is longer. So you are about right now with husband at 54 to set this up if you want.