stroking a 383

do I use 383 Pistons or 440 pistons thanks

Neither, you use stroker pistons.

Not sure you are aware of this but you are asking questions that we were answering 20 years ago. There is a 451 sticky thread that you can take a look at as well as a bunch of tech articles that have been written over the past 20 years. I wrote a book on big block Mopar engines that covered all of this stuff years ago.