440 ring gap

Depends on what you're doing but you should lose the manual for those pistons. On the top ring if you read the instructions they should say something to the effect of .0055" per inch of bore for low rpm/stock, .0075 per inch of bore for performance street/tow, and .0085 per inch of bore for race/NOS. You really need to read the paperwork and use the spec that covers the most abuse it will see. If you plan to race it at all, use the race spec. For the second ring you can use .005 per inch of bore, plus .005. The oil ring should not need filing, just make sure the ends of the expander butt properly.