Joe I have been lucky enough not to have had AMC heads crack on me, and in my personal dealings ( parts, and working on customers AMCs), not had to deal with what you have. HOWEVER, if you talk to the "right" people, this is a COMMON problem. Seams with enough HP and compression, you can crack the heads, and they do it right were you said, on the ledge, front or rear where the head bolt is across the corner. I also believe it might be due to improper head dowel alignment, or something to do with the head binding up. Anyway, these heads a routinely welded. It can be done, you just have to find the right place. Cost is the next factor. If you don't fix the heads, don't toss them, some one will want them, sooner or later Andre " A.J." Jacobs, web page http://southtexasamc.tripod.com (830)-980-3165 , akjamc@xxxxxxxx Owner & Proprietor, South Texas AMC