Every detail of that cab tell me it's from '76--mid'80s.
The speakers don't look like Scorpions or Black Widows to me from the front view.
The horrible round casters, deeply textured (yet tough) tolex covering, small chrome corners, logo size, etc make it an exact match to the one my bassist Mark had in the late '70s.
I played through that cab many times, too, and was always impressed by it's tone, responsiveness, ridiculous volume, and indestructibility.
I'm fine with being proven wrong, but I'm pretty sure you have THE most legendary Peavey bass cab of all time.
They made a LOT of them, because it was a great design.
It's big and heavy to be sure, but so are many many cabs that can't touch this one.
And yours is in unbelievable condition--most I've seen lately are beat to heck from being used constantly for 40 years.
Open it up and look for ID #s on the drivers. That should help nailing it's specs down.
The front grill frame is actually held down to the baffle board with a sturdy hard plastic version of velcro, if I'm right. Instead of hooks and loops it's more like interlocking nipples.
Use a thin flat screwdriver or 2 to pry it loose carefully, working your way around the edges, then you can pull a driver out and look inside for treasure.
Replace the casters with 4" wheels. $4.00 each from Harbor Freight--thank me later.
I want to say it handles 400-600 watts RMS at 4 ohms, but it's been a long time.
Peavey most probably has the owner's manual buried in their website somewhere--they're good like that. Or ask on their forum.
The holes in the driver dust caps says Peavey speakers instead of Eminence, as I recall. Not that that's a bad thing.