Engines like the Windsor, BBC 454, SBC 400, Chrysler 360, etc. are externally balanced (manufacturer's preference, also possible to balance internally) using components attached to the crankshaft but outside the engine block.
Generally, this is done by adding a fixed weight (Windsor dampers are 28 oz.) to a conventional flex plate or flywheel and/or similar to the damper, so that in future these weights will always be correct: the final adjustment is done by machining the crankshaft as usual.
Unfortunately, placing the weight outside adds some bending motion to the crank so the consensus appears to be: use it if you have to, but for racing try to make all adjustments internally. This is where Mallory metal (Tungsten alloy) is used to make the counterweights heavier.
The 230 and 250 in theory would benefit from a different damper, but the .28" stroke difference may change the crank's harmonics so little that the same damper will be close enough to work on both.
