Rero fit roller cam & lifters into early block?

Most of the off the shelf HR cams are not ground on a billet(steel) core, so a std dist drive is good.
I even have a Comp 20-740-9 in here now, its a solid roller cam and it is not on a billet(steel) core, so a std dist drive gear is fine on that as well.

If your not sure, call and ask the cam company and they will tell you.