[hobgoblin351]

Bmxmon has the right idea. But when you drop in that 302, you will need the right motor mounts. And, You should go with heavier springs up front. They're not that much. Next, with all that new found power, make sure you can stop the thing! Front disc brake are a nice upgrade. You'll probably have to shorten the driveshaft. But, you can just have the old one cut. Then worry about the rear end when you get a chance.
Hey lets face it early stangs are not as easy to come by as they used to be. In decent condition, with a V8 they do catch a good price. If you've got a place to work and if.....this is a big if.... if the 66's body is in good or better condition then go for it. If it is a rust bucket or needs to much structurel work find another project car and use that one for parts. Good luck!