The info I've found seems to indicate the only way to know is to check your car. On some there is 1 round, and 1 oval bushing, on each side. Easy enough to feel the bushings and see if there's a flat side on one. I was happy to find only round on my 68.
The most common are round. If you look at the bottom A-arm, rear mount, you can quickly tell if you have a round or oval.