I wouldn't worry too much about the maker, rather the specifications and frequency responses of any speaker you fit in them. Fender started with a mix of speakers, then settled on Jensen, but then used JBL for some of the higher powered amps and then swapped to Eminence or re-badged Eminences for a long time. Now they offer Jensen, Eminence and Celestion depending on the amp or special editions of their standard ones.

Some of those Eminence speakers are very heavy. I've recently bought a used turret post hardwired Fender 5E5-A (Tweed Pro) conversion of a Blues Deluxe (using only the cab, chassis and input and output transformers from the Fender). Whoever had it before me had fitted an Eminence Redcoat 'The Governor' speaker in it. Weighed 13lbs/5.9kg on my digital scales (it's supposed to weigh less). I replaced it with a Celestion Neo Creamback that weighed 4lbs/1.8kg. That's a lot less weight to lug around!

But any 4x12 cab that can handle 300W+ needs to be sturdy or it will add all sorts of resonances of its own. So the wood itself needs to be pretty solid and heavy, so going for light neodymium magnet speakers would be a good move (though expensive).

But you may find that the amp is just too loud for your needs. Most valve amps need to be turned up to a reasonable percentage of their output volume before they come to life. If you were a pedal steel or lap steel player then it might be ideal as you can get loads of clean volume from it, but unless you were touring stadiums, then it's probably too loud for rock use.

I'd look at renovating the head first and getting the woodwork looking nice, then trying it with a borrowed 4x12 cab (or two) to see whether you think it's your style of amp. You may be better off selling it on for a profit and getting something that's a bit more your style.