The license is GPL v2; you might want to consider using “Version 2 of the GPL or any later version” as GPL v2 is unfortunately incompatible with the Apache license. Also, the GPL v3 is becoming more and more popular nowadays.
This means you could keep the project under GPL v2, but people would have the option of using a later GPL version.
I've never liked this idea. What's to keep the FSF from adding a "you give us royalty-free rights to all your patents for eternity" as a clause in GPL v4?
The author is never forced to use a later version. "Version 2 of the GPL or any later version" simply means that distributor (other than the author) can choose between using gplv2, gplv3, gplv4 and so on.
The author is always free pick any license of their choosing for work that they have themselves has authored.
This means you could keep the project under GPL v2, but people would have the option of using a later GPL version.