The other option is to use the old style head. The only dome pistons I have ever seen for the old style head had a full dome.
I wish I could find a 1959 part number reference searched the internet nothing, and my repair book for 1959.
Those books are on the bottom of the pile I'll try to get to them tomorrow.
The rods are all the same length. The big piston pin were only 302 I think. Pretty sure the wide tang was only the later engines which is the number I posted. I'll see if I can find a Perfect Circle or Federal Mogal piston maybe TRW number.
Here is a Link to a thread on the HAMB .
LINK It shows the full dome piston used with the Old open chamber head & the H head. Below in the thread there are drawings of the dome piston in the old chamber and two flat top pistons with the 302 head, D chamber. The late 270 head is more like the 302 head than the open chamber but not the same. The pistons you found will not work with the old head or the 302 head. I believe they are late 270 aftermarket high compression pistons.
Jim Carter used to sell them on special order. He may be able to help.
LINK
