I hope it's worth something... As much as I chucked for it. I found some 61 mid December dated heads I may be buying. My car was assembled last week of December so I the heads may be too late.I believe your block has been decked. That's OK ...it would have been nice to have the original stampings.
But.............that is a very early block. I don't believe I've ever seen such an early casting date...June!!! The earliest I've seen is July. Cecil can chime in here. I think you have a very valuable block here.