17" Wheels on a 69 Dart with Stock Suspension

I just went through this on my Dart, only I added more complications just for fun. My setup is 17x7 on front and 17x8 on back. My front tires are 215/55-17 and my rears are 235/55-17 Yokohamas. I agree with 69_340_GTS on the tire size. My tire sizes are a little bigger than the 225/50-17 he recommended and all the stars had to align to get them to fit right. A for tire availability, I use Discount Auto Direct to search for tires by size. There are many tires in a 225/50-17.
Your first concern will be who makes a 17" wheel with a small bolt pattern. They are out there. Your other concern will be correct backspacing for the wheels if you change to disc brakes or bolt pattern.