should I buy

I would rather be wrong trying to help somebody than by judging them.

But that is my opinion.

@sweetlea welcome to FABO.

That car looks like a pretty decent project. The brake fluid is probably the correct call by others here for the wet floor. As mentioned, looking under the car will tell you how well the work was done and if any was cobbled in. I suspect by the pictures the guy did a decent job because of what he has acquired and was doing. The mixture of the 68 front clip on a 69 is something I would not hesitate to do myself as the grills are easier to come by and cheaper. I prefer the 68 nose over the 69 anyway. That part does not bother me at all. It is a slant six car so the guy was doing whatever he wanted without sniveling from the purist crowd. The fact that is was a 3 speed standard is a bonus. The pedals on the floor are kinda pricey. You could sell those and put the proper brake pedal in or you can easily convert to a 4 speed should you so desire.

I feel that if that engine runs, (I bet it does, the battery is in the car), has solid quarters and body, (not a bondo bucket), and the paint is decent, you will never get this far into this amount of a car for 12k. Certain parts for Barracudas can be hard to come by and pricey, (the rear window trim for example, but I suspect it's in the car), but it looks like he had most of it. Assembling it from the state it is in will help you learn about these cars. If you decide to purchase the car, this site is a wealth of knowledge.