I think your referring to the the black smile on your stomach with a sock steering wheel after driving for a bit :)
I've actually found that I use the flat top more than the regular as I bend more sheet metal than bracket items... at least over the past several...
I'll also add that I have run neutral balanced 225 flywheels in 231s - and that is what is in the '63 build I'm doing now. I also replaced one...
Time for a little update - fitting stuff in as I 'roll off' from work and still strengthening after the 'surgeries'... Anyhow - Got the spring...
Worth it after years of fighting with bolts on many motors.
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