The reason you might have the 1:1 figure in your head is that in ruminants, very generally and approximately speaking, there is around the same amount of saturated and monounsaturated. And those two compose the great majority of the fat -- there's usually a small amount of PUFA along for the ride. So if you think that ruminant consumption is optimal, then you'll think that such a ratio also is optimal. See this set of data, for example, for grass-fed ground beef.

There are also good Paleohacks discussions on this, including this one and this one. The ever-helpful RobS (formerly Rob Sacks) posted a great chart in his answer about "waxy fat" here. (Just ignore my inane questions about eating candles.) In the chart you can see how fat composition varies between different places in the whole animal. There's a link to the original study also, and other relevant studies.

As an aside: you ask about FFAs in your question. This usually stands for free fatty acids. But fats are usually in the form of triglycerides when they are in food. Just as you usually store your fat as a triglyceride, so does the animal you eat. A triglyceride is just three fatty acids (long chains of carbons with hydrogens on them, basically) all attached to a glycerol molecule as the "backbone." The fats have to become detached from the backbone (or one can stay on) to make it through your gut wall into your blood. They are then reassembled into triglycerides to get shipped off in little containers (lipoproteins: like HDL and LDL for example, but at this point the kind of lipoprotein used is a "chylomicron") to various places. Triglycerides are also broken down in order to make it through your cell walls, and then reassembled again into triglycerides inside the cells for storage. But at any given time there are also always free fatty acids floating around in the blood stream, sometimes more, sometimes less -- though not inside the containers, the lipoproteins, but not unaccompanied either (since fats are insoluble in blood): they're attached to albumin, which I don't know anything about or understand. So those are the FFAs. Everything else is triglycerides.

Sorry if you already knew this, if you were just typing casually above. Then I guess this is all unnecessary, but I kind of wanted to see if I could spell it all out for myself anyway, and it was fun.

I like Paul's answer because it indirectly answers the question with some interesting added information as a bonus.

It is my understanding that your body will treat SFA and MUFA very similarly, as neither are prone to oxidation and both are healthy sources of dietary fats. There's no real need to watch your MUFA intake, save for the fact that most MUFA comes packaged with at least some PUFA, as Paul alludes to in his answer. In some cases, especially with some oils, MUFA and PUFA are about even. Those are the oils you'll want to avoid, with one exception, cold pressed sesame oil, which has some poly, but is rich in anti oxidents so it is not prone to oxidation.

Optimal Ratio: I would say get at least 90% of your fats from a combination of SFA/MUFA and less than 10% of your fats from PUFA. So if you are eating 50% fat altogether, you would eat less than 5% of your calories from PUFA. And unless you sit around and eats nuts and avocados all day, I think eating "Paleo" will automatically give you more SFA than MUFA anyway, so personally I don't keep tally.

I would like to know this too. Usually my saturated fat intake is much higher than my monounsaturated fat because I consume a lot of coconut oil. Hopefully I am not creating an undesirable imbalance.

I've never heard anyone say that.