The last one I spent any quality time around one was some 35 odd years ago, but I still remember how that rig sounded; fantastic, like butter.
It was a full Ampeg stack, a V4 head and a pair of V4 cabs. It stood out because at that time in MY mind a 412 guitar "stack" was a Marshall, Hiwatt, maybe Orange, never really considered Ampeg as a worthy contender in the guitar world.
That particular rig was a real eye opener for me.
I roadied for that band for a couple of years, and every time I heard it I swear it sounded better, don't remember what they were loaded with so I can't help you with that. I'm sure that the amp and the phenomenal guitarist using it (Jeff Taylor R.I.P.) contributed mightily, but that rig was absolutely killer.
Have you checked eBay completed auctions to see what they are selling for? I haven't looked myself, but I betcha there are some on there you could use to estimate value.