Thinken a head.Head gaskets.

my opinion has always been that even the .039 thick fel pro gaskets are thicker than the factory steel. You could easily mill .030 off the heads when using fel pro (a good gasket by the way) and not really worry about pushrods, intake alignment, etc. Most of that .030 will be just getting back what you've lost by going to a .039 gasket over the factory steel gasket. I've done .040 on some small block heads and never had an issue.