Tomei "came out" with various pistons in the past, but now no longer list any A-series pistons. Tomei Japan says to contact the local dealers. You'll need to contact these dealers as they generally don't list "A-type" parts on their sites, but they might have old stock on hand.

But why not just buy oversized piston from Nissan or custom pistons companies like PAECO or Arias? They are less expensive than Tomei.

I already own a12 tomei pistons so im not enquiring to buy mate.But i didn't check what size mine were as i assumed they came 76.76mm for the A12 as from wikipedia.Reason im enquiring is because there seems to be no detailed info specifically about the tomei a12 pistons sizes other than that wikipedia sites where they only mention 1296cc tomei pistons or 1270cc nissan competition pistons.
i'll just have to measure mine when i get to it.in the meanwhile i will try and contact tomei japan to enquire exactly which pistons sizes they made only for the a12.
any links,even to old articles with detailed tomei pistons sizes only for the a12 will be alot of help to me.
and thanks for your input dd,
Cheers

They sure did.

Even Nissan pistons come in various overbore sizes. Not so unusual.