I used to run a combo like that . J heads mildly ported, kb 10:1 ,ld 340intake,
484/284 cam (also had a Hughes at one time but can't remember which cam ran which time), stock electronic ignition , 69 340 ex manifolds , an 833 O.D
and 4.10's. I'd wind it to 5000rpms on launch , shift at 6800 using 1st-3rd
for drag raciing and 4th for the highway.
1.67 60ft times and 12.9@112 or so
Just look at the times those guys run in stock eliminator brackets and they
can't port or vary from factory cam specs much.