So much more to think about!
I'll assume you will roll the 401k into a traditional IRA - correct?
Can he defer the pension and get a higher monthly amount in return for starting it later?
Beyond the 401k to IRA rollover, here's another option for even more to consider:
1) Defer Soc. Sec. until he reaches age 70
2) If the pension can be deferred, withdraw ~$39K/yr from the tIRA. This puts you at the top of the 10% bracket, and you'll pay ~$1800 in federal tax, plus whatever in state tax. Keep $18k/yr for living expenses, and put the remaining ~$19K/yr into a Roth IRA. By the time he reaches age 70.5, there will be very little in the tIRA, but a good amount in the Roth, and the SS income won't be taxed much so you should be in good shape. And that's without any pension at all....
3) If he has to take the pension (or, if he can defer it but gets very little in return for doing so), then follow a strategy similar to #2 but convert tIRA->Roth up to the top of the 15% bracket.
The general idea is to take advantage of very low tax rates on tIRA to Roth conversions if you can defer SS (and maybe the pension). You get the higher SS payments by starting later, giving better protection against running out of money if you live longer than expected.
This may be a lot to take in, and some details have been glossed over, so ask away if needed....