Yikes!!! My local shop only charged me $25.00 to sand blast inside and out! Another $50.00 to powder coat the outside of the drum and the top of the lid, $75.00 total.
If you mean to remove the paint (I would) use an angle grinder with an abrasive disk, not a grinding one. Even a wire disk. Remove all the paint! Drums will not be painted with food safe product. That, or sand blast it. A local shop said they would do my drum for $80, inside and out.