Why were we concerned with crankshaft weight in the first place again? R211 posted a nice write-up about the Indians adding weight for more "chug" off idle, but I didn't see what your particular concern was. Revvy race engines usually lighten the flywheels, but those engines are also typically oversquare designs to keep down inertial loading and piston speeds. The long primary chain adds a kg or so of rotating mass as opposed to a crank pinion driven clutch modern system.
You aren't thinking about carving on one of H's $1500 press-together, needle bearing artworks are you? Even the 103mm stroke units can spin up impressively, the 90mm even more so.
Chumma (Ace) welds the old school bolt-together crankpins in place after he's got them balanced & assembled, otherwise they flex too much at high RPM. That's why H's went with the built-up roller crank with wider pins - more shoulder support, greater flex resistance. Chumma also custom makes the crankpin bushes (bronze) and turns the crankpins true round. Ace apparently has had better luck with the bushed cranks than the rolling element units - after the materials & dimensions are massaged properly.
Bullet Whisperers 350 sports a lovingly built & assembled custom crank, so it's actually a "modern" short stroke oversquare engine design, just with pushrods. That's why he gets the RPM he does without fragging.