cylinder head question

I've stumbled across a set of heads stamped 360 4027396, I noticed they have dual valve springs. I was wondering if anyone knows where I can run these #'s or has any info. As far as I know the 360 heads needed to be machined to accept dual springs. I only had a quick look and didn't see any J or X, but they were pretty dirty and didn't want to seem to interested as they might be free maybe