Going only by what I recall having read over the years, cast aftermarket roller cams got either a bad rep -- or a bum rap -- for durability issues with the higher-than-stock spring loads performance cams generally require. They were less expensive and didn't require anything special for a distributor gear, but people tried to use them in applications that really needed billet cores and had problems.
They were (are?) common for SBC and SBF; may have been available for some SBMs, too. I don't remember any cast roller cores for BBM.
The first Isky roller cam that I installed (1971/1972) in a built 383 streetcar was a cast core solid roller 505 T grind, it lasted for ever, (probably less than 5000 miles total) the guy hardly ever drove the car. He had a Super Bird also that he preferred to drive for fun and attention
