12" speaker recommendation for Fender Blues JR. NOS

Hi guys

I'm new to this forum, and I just got a Fender Blues Jr. NOS.  It's the 2nd version of the amp, not the latest III version.  I think it sounds great on it's own as it has lots of clean headroom.  The stock speaker is apparently an upgrade in this tweed NOS version as it is 50 watts.  It can get pretty loud without breaking up.  This is one thing I really like about this amp. I'm not sure what the model speaker is in this amp but I believe it is some sort of Jensen.

However, I like to use pedals with my amps.  I dial in a solid clean tone and use pedals for gain, etc.  When it comes to gain pedals this amp sounds a little less great.  It makes my overdrives/distortions, etc sound kind of shrill and fizzy.  I don't know if this is because of the high headroom speaker or if the speaker is too bright.  Do I need to find a lower headroom speaker or just a darker speaker?  I like how loud the amp can get without breaking up so much, though.  Any advice?  I was hoping for something more British voiced.  I'm considering the WGS ET-65.  I have two Veteran 30's in a 2x12 cab for my plexi that sound great.  I'd like something different if possible, but am not totally against going with the Veteran 30 (if it'll fit). 

Thanks!

johnny gomez