Six Lug Ralleys / Rivits on Hubs

[Thunder Head]

68 c-10 Drum brakes.

I'm sure its been discussed....I just couldnt find it. I purchased some six lug ralleys from Summit and when I installed them on the front of my truck, the back side of the wheel is hitting three rivits. This interference will not let the wheel seat. The rivits appear to hold the brake drum to the spindle housing(??) You know....where the wheel studs are. They are not hitting the studs just the rivits in between the studs. Can I safely grind these off or ??