Question and background:
I am 74 years old and retired. Can I roll over part of my 401(k)'s Required Minimum Distribution into a Roth IRA after paying the distribution's taxes? -- I'm only looking to rollover part of the distribution. They are forcing me to take out more than I need and I am afraid of running out of money if I live too long. Bill
Unfortunately, no you can't. And since you're no longer earning an income from active work, you unfortunately can't freshly contribute the after-tax distributions to a Roth IRA either.
Of course, you can take whatever you don't need and invest it in a regular investment account. While you won't get the same tax deferral, that should help with your concern about running out of money.
I don't know your situation, but an idea that has helped folks in your situation is an immediate annuity. You could roll some or all of your 401(k) into an IRA and purchase an immediate annuity from an insurance company. It's like a personal pension. You'd only use whatever portion of the IRA that would give you (or you and a spouse) enough lifetime income to take away your worry.
It's not an investment, it's a risk management tool...helping you manage longevity risk. If you live a long time, you "beat the house" so to speak. If you don't, well then "the house wins" (although you could choose a guaranteed payout period). You'd want to be fully informed of the trade-offs.
I'd encourage you to find a fee-only financial planner with a strong insurance/annuity background that can review your financial picture, help you run retirement projections (longevity vs. resources), and then help you choose the best solution(s). Be careful of consulting an annuity salesperson on this...it could be like asking a barber if you need a haircut.
Hope that helps. All the best!