Ok mid 10s... I'm newer to the Mopar world but I have taken a Chevy 355 with steel head nothing special in a non gutted Malibu and went 11.50s on the motor & 9.80 on spray. So I figured a Chrysler could do it aswell without ton of high end stuff. I admit I do feel a solid roller & a trick flow head would get me there but was looking to see how close ppl have come with a lesser combo.
FWIW, a ported X, J, etc…. head is capable of approximately 275 cfm. Beyond that, it’s larger valves and port adjustment for the larger valves. I would not expect much more.