I need help; what to do about my aging rig...

Hey all. I have a quandary & I'm not sure what direction to go in. I have a great little rig that works for me, but it's getting a little old. Some problems are developing.
So, the rig: An SWR 350 burgundy face head pushing either 1 or 2 (depending on need) Ampeg portabass PB212-H cabs. I know these cabs were not popular, but I just LOVE the form factor of them. The sound is just OK, but not in a bad way. They work for me. I want to continue using these; more on that later.
The head sounds good, & has *just* enough power to run these cabs, be it 1 or 2. (Head does 2 ohms, but it's rare that I use it. Normally it's 4 ohms) (Cabs are 4 ohms each) Yeah, I know...
Lately the fan in the head has not been working right and the head has been getting very warm on the past few gigs. I've suspected the "thermostat" for the fan had been on the way out for a while as I heard it running very sporadically during gigs in the past, but felt cool to the touch. Lately though, it's been getting really warm and I don't hear the fan anymore. So there is a problem there.
I bought a used Headlite as a replacement to the 350. It seemed to me to be the perfect replacement; 400 watts, basically an updated version of the 350 but in a class D format. Unfortunately it doesn't do 2 ohms. And apparently, either I don't know how to dial in a sound from it, or it really is missing something, but in one band I'm in everyone noticed how weak it was. I was not happy about that, as I feel like it was laughed off the stage. Looks like a CB radio someone said. So I don't use that.
Did I buy the wrong head? Obviously I need to repair the old one. Or should I think about another head?
Secondly is the cabs. Maybe I should start a separate thread for that? I may need new speakers for them. One pair blew out from the headlite. I replaced them with some carvin 12's I had. It works, but that one cab is not ideal & not matched to the other one. I've been reading about some neo replacements, and wonder if this is the right way to go? Eminence kappalite 3012 looks like a winner, no?

I've been intrigued by the GKMB500 combo W/ 2x12's. Then I saw the new Fender rumble 500. First off, I don't want to buy a new amp as I like my old setup and I'm not sure a combo would cut it. Yet the specs on these amps seems good. What am I missing here? Help.

 

I don't need or want to sell it. I do need to fix it though. I need a source for a replacement thermostat. That's my 1st problem.
The cabs is where it gets stickier. I really love the form factor. 2x12, 400 watts, 30 some odd lbs. And built in dolly/handle. What's not to love?

 

2 ohmers are pretty rare actually. I know carvin does some. I have an iAmp 800 and that does it too. But all the other big guys don't. Especially class D. Maybe someday. In the meantime, I suppose the fan fix is fairly easy. I know I could fix this myself if I could just get the right part . Anyone know the P/N for the thermostat & where to get it? (Kinda what I'm looking for here to start with.) Thanks.