840cpl cummins

I have a few questions, question 1 should the pump for this cpl be a afc pump
2 what should fuel pressure be, it's showing 100psi rail pressure right now
3 can this engine and pump set up support upgraded injectors. It does pretty good right now but it's definitely not the power of the old motor that a driver tore up, the old motor was supposed to be rebuilt and the fuel pressure hadn't been touched, all it had was a 17 button
Current pump has a 17 button in jt now, I checked out of curiosity.

Have the old engine that cracked a piston planning to build it to 550-600 next year or so
Does any one sell steel pistons for these or are we stuck with the aluminum pistons, I understand I need to match cpl for new parts, I plan on doing a complete rebuild, cam, crank, pistons, rods so forth can some one tell me the best cpl to get for matching parts for these goals.