I would retorque the inlet manifold, fit a wideband O2 A/F gauge as a data logger to check A/F ratios while you're driving, and check the plugs again in 2000 miles.
One of your plugs in the early photos has a large glob of carbonised
oil on the insulator.
I'd also say that your Air/Fuel ratio is a tad rich.
What carburettor are you using?