I have a short deck r3 that I am building. I have a 3.79 crank for it. It is a 9.20 deck block so I need a custom piston. I am thinking to make it a 4.230 bore to make it a 426. I started to look into ring it is kind of a odd bore with out to many off the self rings. I know I can have custom set made. A ford 427 is 4.233 could use them but they are kind of odd ball to. Was wondering if I would be better off going with a 4.185 that is a common sbc size. I can get a chevy piston with a real close pin height to what I need in 4.185. I dont know if its worth it with the amount of valve machineing that it will need.

Look on ebay for 4.230 piston rings, many show up.

I would give Total Seal a call and get their take on it.

Go with the 4.185 bore.. the whole build would
be easier and cheaper

I'm building a 9.0 deck block with a 4.185 bore 3.70 stroke. I had Diamond make me a set of pistons. I had special valve pockets machined. Diamond made them with no problem and the price was reasonable. W8 raised seat takes a deep seat. Brett Miller gave me a piston number with the correct seat and they used that with my other specs. to make the set. Worked out perfect. I can give you the piston number if needed. They came with Total Seal rings that are readily available.

You sonic check the block to go 4.230? Would need a really good block to do that.

The block is a siamese 59* one of the ones with the wrong cam tunnel. It is at shady dell now. Ryan told me dont worry about sonicing it till over .250. Its going to stay 59* with a set of w2's.