Sorry about your dad, I lost mine fairly recently also.
Those are pretty rare; I can't even find a "Model 9" in the catalog archive thread.
They are worth what someone is willing to pay, period. The only way to determine what they are "worth" is to reference what someone has actually paid for them, but that will likely be extremely hard to do considering the rarity.
That era Sunn PA cabs aren't generally considered to be very collectable though. Not old/high end enough to be vintage cool, and too old to compete with the current crop of light weight, ultra efficient boxes for actual sound reinforcement.
Not that they can't or wouldn't be used by someone for that purpose, or that no one would want to buy them, just that for $250-$300 or so you can buy a set of speakers that weigh half as much and are 2 to three times more powerful as those old Sunns; with the power amps, DSP, and a two channel mixer already built into them.
Keeps the market value down, just another victim of technology. What is a 26" Sony Trinitron worth today? I paid over $1000 for one in early 80's dollars...
If you are trying to sell them, put them on eBay and see what they bring, or determine how much you would take for them; what amount of cash you would consider to be worth more to you than those speakers, and put them in the classified section on this forum.
Your post kinda seems like you are fishing for offers, so you need to determine what you want, or if you are going to keep them fairly soon. If you are going to keep them, what does "how much they're worth" really matter?
