i did the same thing except i used 9/16" solid stock(i also use it to align tabs from pass to driver side when building spring hangers/link mounts etc)I took one of these and welded it to a 1/4" rod. Chuck in cordless drill and have at it. Push the big stuff out first with a piece of pipe and a wadded up rag. Use lots of WD40 with the wire brush. Repeat until clean.