318 stock pistons

my 1967 dart, coronet, charger factory service manual. shows the stock 318 piston with 4 valve releafs in the top. factory over sizes .005" .020" , .040". in the past i have seen .010" over size from the factory in a 440. and no after market pistons come in .010 over eather. but the .010 oversize is NOT available from the factory over the counter.. ill guess the ,005 oversize is NOT available ether.