Drums from a 7" 1/4 fit on 8" 1/4?

Aye yai yai! First, again, if your car is a '66 A body that's gonna be a tough fit putting an FMJ rear in it. Besides cutting the driveshaft, cutting & moving the spring perches,
setting the pinion angle, setting up the gears, & do You know which gear series carrier the SureGrip is, You're going to have to pick an oddball wheel offset to put the tires
where You want them. They made two carrier series for the 8 1/4, if the SG came from a rear that had the cruiser 2.45:1 gearset, You cannot use it for higher ratios like
3.55's, just FYI. Whenever You buy brakes/hardware, get everything for the same vehicle, there was a change in shoe & wheel cyl. style that has to go together.