The Security Six was a superb revolver, I am guessing their safety concerns were solely due to their adoption of the .357 magnum earlier, they probably feared one of their personnel cramming a heavily roll crimped .357 into the cylinder of a .38 Special, which I have seen done and could be pretty catastrophic. (The .357 magnum is intentionally a tad longer than a .38 special to try and prevent this. But if you put a heavy roll crimp and seated your projectile deep enough in the cartridge, you could force a .357 magnum into a .38 special chamber and the resulting pressure on the mouth of the case would drive those pressures dangerously high, supposedly some factory .357 rounds could be made to do this although I've only seen it replicated with handloads.
[b]Needless to say do not try this!![/b]) I do remember CHP toying with the idea of supplying their Admin' personnel with .38 Specials (theory went something like 'They are more likely to survive being shot with their own .38 then a .357 if it was wrestled from them.') Which was ludicrous, but indicative of the lack of experience and less than intuitive nature of California Law Enforcement Administrations (not individual officers) at that time. That would suggest a shorter barrel though.
The CHP area teams competed in our PPC matches back then. Ammo was generally .38 Special wadcutters and they could foul (leave a lead ring) .357 Magnum chambers so nearly everyone went to .38s (some or most with custom heavy barrels.) It seems more likely to me that they were requested by one of their Range Masters for such competitions and then under review nixed due to concerns over the afore mentioned potential breech of safety with the .357 magnum in the .38 Special cylinder problem. The fact that yours comes with a 6 inch barrel points to this conclusion as well. Unfortunately the two California Range Masters that I knew are no longer with us, so I have no source to check my conclusion with. (That's what you get for outliving everyone.)
Value, not sure, everything now is ridiculously high!
I have a Ruger Speed Six with a 4 inch barrel in blue with the marking ""Made in the 200th Year of American Liberty' on the top strap. I have carried it often and shot it tons, but a few local dealers have seen it and appraised it in the $200 to $250 range which I would think was low. However I've seen a 'Liberty' MARKED 6 inch blue .357 Magnum Security Six in much the same condition at a Phoenix gunshow with a $500 dollar price tag, which confirms the time honored theory where its value is dependent on whether you are selling to the folks behind the counter (or table) or buying from them. However your Stainless .38 Special 6 inch CHP marked Security 6 should best that price some. I'd get as much paperwork as I could for it while you still can (from CHP and Ruger,) it makes a real difference to a collector!
Wes Cowan's (Cowan's Auctions, Inc. in Cincinnati, Ohio) auction house would fetch the best price, if you get a good provenance on your revolver. And that is heavily influenced by the economy (which is now pretty bad,) so you may want to hold onto it if you can.
Thanks for listening to an old dinosaur!