+1 on the crank pulley. Fluidampr or oem is the only way to go. Especially with an uprated clutch and flywheel and due to the fact the engine doesnt run balance shafts also, if there isnt any type of damper on the crank it will cause serious harmonic resonance which is basically very high pitched frequency which will cause serious damage to the rotating assembly including especially crank, bearings, clutch and gearbox. So for the weight saved with the n1 pulley and the potentional damage caused to the engine or the extra kilo and a balanced engine, i know which i would prefer.
Good work with the build process so far, keep it up! When do you think this will be finished?
Ben