Thought it was an earlier B rear, yeah you have to move the perchs.
It's going to take a wheel with a ton of backspace. The rear is about 6" wider than a stock A rear. The 68-70 B rear is only 3" wider than a stock A.
If it has a sure grip, see if you can pull the pumpkin first to verify, it's a good deal at $120 regardless of gear ratio. Sometimes, you can look in the fill hole and see the carrier.
Good luck