Timothy,
I want to re-iterate what Otto has told you. If your brakes aren't functioning properly, a few relatively inexpensive investments can repair your drum brakes to top shape. There are some that claim you must switch to disc brakes, but trust me, that is not going to help you that much. You can make any brakes, disc or drum, fail if you intend to drive a certain way. Regarding the brake system on the 66 Toros, there are 2 things that you could do that would be a well thought out upgrade: Change the master cylinder to a dual master cylinder, and add a distribution block and proportioning valve. Olds added these in 1967 to the Toros to address some concerns about brakes, and that was basically what happened industry-wide though.
A better investment of time and a little money would be to check the rear trunk area drain tubs to make sure water is not collecting in the car and causing further rust (it's likely there is some). Other rust areas to pay attention to are the windshield (rust around top of dash , especially around A pillars), and the floors, especially in the rear seat foot floor area. Bad rubber around the quarter to door window glass will leak water in there which collects in that area. Get your windshield resealed with modern materials unless it has been replaced in the last 10 years or so. THe factory windshield sealant used goes bad and allows water in.
As long as the engine and mechanicals look robust, you just need to do the basic maintenance there. I would check out your carburetor carefully. These Quadrajets tended to develop fuel leaks, which could lead to and engine fire if not addressed. make sure that all seems to be working fine. Repair and replace whatever vacuum tubes and wiring issues you may have. The car will run fine then and give your years of enjoyment. If you don't think the engine has ever been serviced, when the right time comes, you will have to change the timing gear and chain. The original gear was nylon coated (to make it run more quietly) and those fail eventually. The nylon pieces end up in the oil pan and oil pickup tube screen. Otherwise, these engines are well built and designed and proper care will help you get many years out of the engine before overhaul.
Where are you located? Great to see young folks interested in these cars! They really were muscle cars, but with class and at the time, state of the art engineering. And you are in a unique class. There were not many Gen I Toros made -- rough estimate without checking the data is less than 140,000 cars produced in the first generation (1966-1970). The more you learn about your car the more you'll really appreciate that. Here is the FB page for the restoration I'm doing on my 67 Toro. Don't do this type of thing till you're ready for that -- it's expensive and takes a lot of time. Drive and enjoy your car --take it to car shows. You'll be the only Toro there. By doing simple inexpensive maintenance items now, you can enjoy your car for a long time.
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