The C6AE-R heads are nice runners with a little work. Lots of guys prefer to use these heads. They have 71-74 cc chambers and stock valve size was 2.02 in and 1.55 ex. They are listed as a 352 head but some have found their way onto 390s. The date code is above the casting number under the valve cover area. It's between the center two valve springs. Look for a number/letter/number sequence like the date code on the block. BTW the date code for the block is below the oil filter adapter mounting pad on the block. It's on the small angled ridge. If you post them I can let you know the born on dates for them.

G.