"New" is not necessarily good, since you don't have any history of prior performance. Too bad you had to learn that the expensive way! Yes, all inline 6-cylinder engines are inherently balanced, although harmonic balancers and flywheels can change that situation. Good luck on the latest buildup!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!