I'm rebuilding an 1970 455 F block and I was cleaning the pistons when one of them fell off the table and a piece of the bottom broke off. So I'm trying to see if anybody would know where I could get 1 original replacement piston? if possible so I don't have to spend money on a whole new set of 8.

I currently have all original cast aluminum pistons with stock gm connecting rods. According to the research I've done it says the compression is 10.5:1

 

See if it’s standard bore, post that, someone on here will have one.

 

This is my first build so im still learning correct me if im wrong but If I had to guess it seems to be standard bore because theyre all original pistons and rods but it has in certain cylinders on the head of pistons there's a B or C stamped on them and on the deck also, I was told those B's and C's are for a different measurement?

 

If you can post a picture of the top of the piston or PM me and I can see if I have a piston for you, I need to verify the top configuration.

 

When you do find one dont try to press the old one off and install the new one yourself. Take it to your machine shop and have it done properly with a rod heater.

 

I do remember reading somewhere that the letters on each cylinder indicating a specific bore size, and the guy putting the pistons in on the assembly line knew which size piston to install to maintain ideal piston/wall clearance. I don’t remember if the pistons also had identifying marks. I’m guessing after 50 years, the original bore size wouldn’t mean much now.