It's kinda tight in there and desoldering chips is a pain anyway, not to mention risky if you accidently break a foil trace and don't repair it before installing the new chips. You end up covering up your mistake rather well. As a tech, I desolder the original and put in a socket. That way, I have the option of putting the old ones back if the upgrade doesn't work for some reason. You never want to solder on the board more than once if you can help it.
Sockets are cheap.
That's much easier on the board, but obviously destroys the chips. The Jameco part number for the chip is 41582 or 41574 or 41611. Those three numbers represent the same chip, but at different speeds, 120ns, 100ns, and 80ns respectively. Jameco has the sockets too. For desoldering, you'll want an iron of about 25 watts.