Those may be a high compression version. I'm not sure. The pistons in my '57 270 are flattops. I don't know if that if stock? I built it in the late '70s. I think those will work for you and I'd grab them before someone else does. These and the ones with the other engine seem to be your choice right now.

I'll try to look up some some rod & main bearing numbers this afternoon.

"I wonder if God created man because he was disappointed in the monkey?" Mark Twain