by "large front drums" do you mean 10" diameter or large(4.5) bolt pattern?
normally the 66 cars came with a 4" configuration with Left and right threads.
the Crager S/S has a thin wall lug that fits down inside the hole, ie. the stud will not stick out like a regular steel wheel that uses a tapered mount surface.
most folks change the left hand studs to right so that unknowing helpers
don't wring them off.