C-body LA cars (starting with the '65s, afaik) came without front sway bars from the factory. So that addition alone will make a big difference. In the original runs, the body lean was not bad by GM standards, fwiw. The car with the front bar added was a good bit flatter at the slightly-higher speeds he was running. The front sway bar plus the tubular upper control arms will really make a difference on highways at higher speeds, I suspect.
Thanks for posting,
CBODY67