Difference between '70 and '71 & up pistons

I was hoping the second one from the left was a 71 . Not so, itsa 70 with the center pin removed...
I can only guess at my CR without that number....
L2368, which is a Sealed Power forged replacement piston 71 455...

Jim

 

Here ya go. Check your compression ratio to the nearest tenth of a point without taking it apart.

https://store.katechengines.com/mobile/whistler-compression-ratio-tester-p174.aspx

 

You buy it. I'll borrow it...

That would be great, I would be interested in the dish cc of the 72, probably get me in the ballpark , at the very least...ty, JIM

 

I had that mirror as well and didn’t have much luck with it. I don’t remember the details but I think the mirror reduced the field of view by a lot.

 

Wondering if we did a group purchase, say we bought 10 of 'em we'd get a few bucks knocked off