As long as the naked lead slug will pass through the choke bored bbl, you're OK. Doesn't matter if the slug is smooth or rifled,,hollow base or solid, round nose or flat.
The card & fibre wads are supposed to be a tight fit in the bore and can easily compress even more to pass through a tight choke w/o a problem.
I wouldn't bother physically attaching the wad to the base of the slug like the Brenneke slug if you had that in mind.
Just powder, over-powder wad, filler wad to bring the slug up to proper height for a roll crimp.
Worked fine for many years that way. Simple too.
