2000s set up question

[meltdown]

Although I believe this set up is likely fine, I would like another point of view.  I have what I believe is a 1968 +/- 2000s head (it does not have the bass boost switch on the panel).  I had the bias adjusted some years ago and one solder connection corrected and it is a monster.  Full jam and I never run my amp volume above 3 (Jazz Bass full on) and it sounds great (but have never changed tubes yet 6550's).  I don't have the matching cabs for this head (damn it).  I do have an original (from Manny's Music 1968-69) Sonic II rear mounted, horizontally ported bottom with JBL D-130F's (2x15).  I have just added this cab on the 4ohm extension outlet.  I run on the 8ohm main speaker out a front loaded vertical side ported Sunn 2x15 cab (same dimensions as the sonic II) with JBL D-140F's.  The head is definately showing 8ohm main and 4ohm external on the speaker outs.  Are these cabs likely both 8ohm cabs and therefore ok to run with this 2000s?  It is an Allman Brothers 'Whippin' Post' monster.  To add some high end punch (the low end is VERY solid), should I look for a 4ohm SWR or Eden 4x10 with attenuator for the 4ohm external out and ditch the Sonic II?

[EdBass]

Are these cabs likely both 8ohm cabs and therefore ok to run with this 2000s?

Check the resistance of the cabs with an ohm meter, it should read 6-7ish ohms for an 8 ohm cab.

To add some high end punch (the low end is VERY solid), should I look for a 4ohm SWR or Eden 4x10 with attenuator for the 4ohm external out and ditch the Sonic II?

I'm not sure how an attenuator figures into this scenario, but you're better off with two 8 ohm cabs plugged into your 2000S rather than an 8 ohm and a 4 ohm cab. Experimenting with a 2000S head using a D140 loaded 2000S cab in conjunction with a  Hartke 410XL wasn't very satisfying, the JBL's overpower the 410, but I've run a 2000S through a pair of Hartke 410XL's with very punchy results, and it still has a very solid bottom. You do have to drive the 2000S substantially harder to get the same stage volume level but it actually sounds pretty cool, much more modern sounding than the JBL's except it kind of snarls and growls, but yet it seems to stay focused and reasonably tight.