Speaker for a 6g3(brown face dlx) circuit?

I have an Ampeg j20, which is a 6g3 based circuit, I have modded it to be closer to the original fender 6g3 circuit. The amp had an Ampeg branded 12" alnico in it when I got the amp 10 years ago, I found the high end to be to harsh and the low end to be very fluby any time the amp got tuned up past 4. It currently has a celestion greenback which is okay but a little to miss focused for my taste. I mostly use this amp for blues and country. I love the John Mayer, SRV , and hendrix type tones for blues, and for country the chris stapleton tones, or early stuff like Waylon Jennings in Merle Haggard. I'm considering the blackhawk, and the WG12A.