You don't give any details about the frame's tubing. As a former custom frame maker I can tell you that the center sections of thin gage Reynolds and Columbus tubing are really thin and VERY fragile. YOur method might depend on how the various attachments were installed on the frame. If silver soldered I would gently remove them with a torch. If brazed with brass that's a dangerous method as 531 tubing can be cracked by repeated heating to brazing temp. I personally wouldn't have the cojones to grind them off. It's yer frame, do with it what you will.