Yes, they will work (my '66 came to me with 71 spindles, rotors and calipers and 14" 10-spoke Shelby-style alloy wheels).  If you have mag wheels with the stick-on balance weights on the inside of the rim the caliper will scrape them off though.  You should have no issues with steel wheels.

The spindles will bolt to the car, but you will need to use 70-73 outer tie rods or a pair of my TRB-6570 tie rod adapters.

As for wheels, it depends.  If you have the stock 14" wheels from the 66, they probably are not going to clear the calipers.  But, if you get some stock steel 14" wheels from a 68-73 Mustang or a 75-80 Granada or equivalent, they will fit.  If you have original styled steel Mustang wheels, they will NOT clear those calipers.  It has to do with the shape of the formed wheel center, not the rim itself.  It just depends on what wheels you have.  Also, you will need to trim 1/8" from the adjusting threads of ALL FOUR tie rods, plus both ends of both adjusting sleeves or you won't be able to get the 71-73 spindles toed in far enough to set the toe properly on your car.  You will also need to make new steel lines to be compatible with routing requirements of the 71-73 brake hoses.  See my Granada brake installation page for details of all the ins-outs-pitfalls of installing those spindles on your car.  For all practical purposes, the 71-73 spindles are same as 75-80 Granada spindles.

As technomancer mentioned, the spindle geometry is different.  The radius arms are not longer, but they do point more towards the middle of the car than the stock 65/66 spindles.  CSRP in Austin, TX does offer a Granada spindle with correct geometry for the 65/66, and your brake parts will bolt onto those spindles. 

Sometimes the cheapest parts you come across are the most expensive ones you will ever own.  If it was mine, I would opt for a set of original style Kelsey Hayes 4-piston brakes that will bolt up to your existing V8 spindles.  If you want, I can email a parts list to put the original brakes on the car.  It may appear to cost a bit more up front, but when you add up all the negatives and collateral costs of installing your free brakes, you might just come out ahead to use them.  I do not sell any of those parts, but I did compile a list to help out those who need the info.