First of all, patience
lots of advice will pop up here, all of it good and here's what worked for me.
The '65s KO's were put on so tightly that they galled, so expect that situation. Pull the center caps and look for any safety pins. Try to pull them straight out. If they do not come out, pound on the spinners AS NOTED BELOW....turn them in the direction that results in the best alignment, even if it results in SLIGHTLY tightening the spinner. Any movement of the spinner is a good sign. If there is no way to remove them, then the pins must be drilled out . If they are aluminum, it's a 15 minute job. If they're stainless steel, it's a 2 hour job and a number of drill bits. No other way.
At the same time SOAK each set of spinner threads with a liquid penetrant (took me a full week of soaking to get the first spinner loosened). I think WD40 is a waste of time here because it is NOT designed to loosen nuts. Buy the stuff that is actually designed to do so (Yeah, I use WD40 for loosening nuts but this calls for the real stuff, save him the grief).
Now comes the interesting part of whacking the spinners off. I use the small short-handled STEEL mallet sold by The Big Orange Box and an old piece of tire as protection against marring the spinner. It will take a long time. Usually better with two guys just because it can be exhausting work and you want to get them all off once one loosens up. The car must be on the ground.
Finally, since I'm a controversial kind of guy, I'll preempt the discussion with my own personal opinion about lead hammers, dead blow hammers, fancy tools, etc. I have bought, and subsequently sold every other gizmo that alleges to loosen knock off spinners. Forget the lead hammer, use it only when you are at shows. Forget the triangular shaped wrench with the polyurethane insert - I sold mine to a good buddy who is MUCH more patient than I am. I just want the friggin' things off and it you're not careful, the handle will scratch the paint around the wheel wells. ASK me how I know. The mallet and old tire are the cheapest way to go and and as good as anything else expect for my blocks of lead.
My favorite tool happens to be a 25lb block of solid lead that I liberated from an X-ray lab that was being demolished. VNV has seen it in my garage and still can't believe there is such a thing. Problem is, you just can't find this stuff if you're a civilian.
The next part is more important. Search the recent thread here about KO's and find VietNam Vett's post of a .pdf file which is the installation instructions for the KO's. You need to pay attention to the fact that the hubs need to be on the correct side and the wheels sit in the proper holes, etc. These instructions are invaluable.
To reinstall, cover the threads with antisieze grease (Yup, that's what I recommend) and install roll pins instead of the solid pins. Mark the spinner and hub with a sharpie (or paint), drive the car for at least 10 miles, park it and check to see if there has been any movement. Adjust accordingly.
The antisieze is important because it makes a big difference in removal during a flat, for example.
Now that they are easy to remove, I would remove the KO's and place them for sale on Ebay. I had two sets and took them off of both cars - I just NEVER trusted them. Never had any problems when I understood what to do but when I was a newbie, I almost drove one wheel off the hub. Never again.