Actually, in my recent experience over the last few days with flashing half a dozen roms and gapps you can't just mix and match as you want.
Certain gapps were made for different versions of android.
For example, I tried several roms built on android 4.2x and was installing gapps made for 4.3 and it kept crashing the keyboard which was great because without the keyboard you can't enter any text or info at all.
I found out later what was going on because I found the gapps repository which included release notes for each gapps zip package and in there it indicated for which android version they are made.
I thought the roms were bad but went back again and reflashed the roms with the older but correct version gapps and then they worked, no keyboard crashes.
So in short, flash the gapps package for the version of android you are installing and then later once you are up and running if an app needs updating it will do so via google play.