I built up a new set of wheels using NOS Shimano DX hubs. When I tried to install the 11-28 tooth cassette onto the rear hub, I found that the cassette is loose and floppy on the hub because of the hub being non-compact. According to Sheldon, all I need to do is add a 1 mm spacer behind the cassette. I tried that and the rivet heads hit the spacer and hold the cassette out too far for the lockring to fit. Is there any reason that I shouldn't just grind the heads off the rivets? Maybe put a little Super glue on the rivet ends to hold them in place? Any other suggestions?