Both of these spindles are designed for disc brakes,so I doubt you could get drums to matchup exactly, but there are a lot of drums out there.

From a performacne perspective, the Fatman's are heeeavvy. IIRC, they are 7-10# heavier than a stock disc brake spindle. But, if you consider the source, they were designed for street rod parade ground crusiers with Volare front stubs under them, so lightweight performance was never a primary considerations for them.