I'm in the process of building a 505ci based on a 440 block. What I have learned with BB Mopar stroker kits is when it comes to compression ratios it's all or nothing. in other words, the dish piston kits typically yield 9:1 to 9:6.with a 84 cc head, the flat top piston kits come in at 11:5 to 12:5. If you want a 10:5 motor you most likely will need to go custom on the piston. I chose Diamond because they are very easy to do business with. I made 1 change to Diamond Part# 52437. Instead the stock 24cc dish I had the dish cut to 10 cc's. Final result, 10:80 compression Not bad for just a few extra bucks per piston Call Diamond and ask for Ron Beaubien, he is a Mopar guy