[Mr427]

YES!
IF you have the engine apart, have it dynamically balanced with the "new" flywheel and front crank spacer / counterweight and harmonic balancer. The crank spacer and as-cast-counterweight, really are the critical part of this setup. The harmonic balancer is less important, although you need a heavier one for higher RPM operations. All that does is really cancel out mechanical vibrations that stem from various rotational misbehaivor inside the engine, stemming from issues like spark plug condition, timing, fuel stability and other issues that ifluence how the engine behaves under various conditions.