hello , food for thought ......I have done this many times .......a 413 bored +.065 ( which is not bad for the old castings) is 4.25 " which is std bore 383 or 426 wedge ! the 426 street wedge pistons are 10 to 1 and they made many different 383 pistons , the thing to remember is deck height of piston in the block . the 383 piston in 413 +.065 bore is low in cylinder so a higher compression 383 piston would get you the 9.5 compression you seek ..KP
