Can I used 205/65/15 instead of 205/70/15 on my crysler concord 95

Since the tires are the same width, but a little bit shorter sidewall it should be OK. My only concern would be decreased ground clearance. The car will be about 1 inch lower to the ground on the shorter tires, so watch out for speed bumps!

Your speedometer will also be off about 3 percent, but it will be showing slower than your actual speed, so it should not get you on the wrong side of the law.

Best wishes.

The tires will work fine, even for permanent use.
The stock tires for your car are about 26 1/2 inches tall, The tires you can get are about 25 5/8 inches tall, Thats a difference of about 9/10 of an inch. The actual difference of the height for your car will be just under 1/2 inch lower to the ground.
As said earlier the speedometer will be off by about 3%, So, at highway speeds your odometer will show about 70MPH while your actual speed is about 65MPH.