Those are a copy of the McLeod weight kits, and are used on a steel flywheel that is flat and smooth on the engine side. Cast flywheels are neither. And beyond that, you still need to know where to drill/tap so it bolts in place.
I am not going to argue with Mr. Brewer! I think those weights are for the flywheel sold by 440 Source though and not a cast flywheel as stated by Mr. Brewer.
