Tuning advise for 360

Hi,
I have a 360 in 66 Cuda. The engine specs are:
cam: 280H magnum(comp)
air gap intake
3310 stock Holley 4160 72front jets plate rear
stock 587 heads(1.88/1.60), speed-pro pistons 9.3 cr.
RN12YC champion plugs
904 w/ 3:55 gears
spitfire headers w/ 2.5" exhaust
The plugs are always dry black sooty

What would you recommend for jets, plugs etc.
Thanks 8)