350 sputtering under load

[jg1977c20]

guaranteed your idle adjustments are too rich -thats why its hard to start hot -but also the visual on those plugs also confirms it -looks like oil was being washed off the cylinder walls , and as mentioned r45 TS is the correct plug -and with a hot ignition you could open the gap to .050

[fxrsrider]

Black soot in exhaust=rich fuel mixture

Pinging under load=starving for fuel (I had a similar prob, turned out my fuel line was pinched between the fuel tank and frame) and/or detent cable not working (I had this prob too) and/or advance curve not in tune (I was about to retune, but fixed the first two and ping went away.....curve was fine....MSD, not OEM)

Fuel filter......use two. One before fuel pump at 170 microns and one after pump at 70 microns (when running an aftermarket electric pump-----is don't use the OEM mechanicals, so refer to the other member suggestions in that case).