Vox AC4c1 upgrade (12" speaker)

I have a Vox AC4c1.  It is a 1x10" set up however I plan on making a 1x12" cab for it.  Right now the amp is pretty bright for me.  Even with humbuckers on my Gibson I have to turn down the treble almost all the way on the amp and the tone knob on the guitar.  So I want to lessen the high end a bit with the speaker.  So the Reaper 55hz seems to make sense.  However, I want to make sure it won't take out too much of the high end.  So would the regular Reaper or the Reaper 55 be best?  Thanks.