So it's illegal to sell a double action, but once it is yours you can convert back to double action legally?
To answer the OP's original question.
I would wait to see the 586 and then decide between the 66 and the 586. I understand things are more expensive in CA but $800 for a 65 is just way too much.
CA has a roster of "not unsafe" handguns. The list gets smaller every year as guns drop off (manufacturers don't renew). The only way to add new guns is to add microstamping, LCI and mag disconnect, unless such new gun can be argued as the same as the one already on the roster. Gun color, sights, place of manufacture, etc. can make a new gun be deemed "different" such as a USA made Glock vs Austrian or the new MC Operator vs the old one, etc.
Revolvers are exempt from microstamping and LCI and mag disconnect do not apply. However, most older Smiths are not on the roster. Hence, Californians have to go through a "loophole" to acquire some of the older Smiths. Such loophole has its limitations, too. For instance, the barrel length has to be at least 3 inches, etc.
In addition, California buyers need to find an FFL that performs the exemption. That "service" costs money, say from $50 - $150+, as not too many FFL's do them.
So a $500 pre-lock Model 65 with a 4" barrel will easily turn into about an $800 revolver after shipping, transfer fees, use/sales tax, conversion fees, etc. I just went through that not long ago...
Then, some sellers don't want to bother shipping to CA as there is an extra form that needs to be completed and most they've heard is that CA gun laws are messed up. They just don't want to deal with it at all. Can't really blame them.
That's our world... I have seen, on many instances, that a pre-lock 686 got bought via private party for $850 with multiple buyers in line as back up. [emoji33] So an $800 Model 65 is not totally ridiculous here. After all, we still observe American capitalism here. [emoji12]