For my 410 sb I am using a 850 ultra and when we ran the motor on the break in stand it was filthy rich.Black plugs,bit of smoke out the pipes,ect.The carb comes with 84 jets all around and 4.5 power valves front and back.I know I have to go leaner but how much?The motor is 410 ci,ported eddys(flow 270 int)10.5 to 1,flat tappet solid,602/624, 262/274 @ .050 inst @ 104.Victor intake,2" spacer.I was thinking maybe 76 jets?