That's from Galen's white books. I have it, too. But I have to question a 64 273 HD bar being .89. Understand that a 64 273 was two barrel only, no Commando 273s until 65.
Agreed. .890 would be a big block bar. No big blocks in 64-66. Even a 1968 340-S would be a .870.
That said, I put .890s on my 67 273 Commando car. I think going one step up is a no-brainer for any street car — they were all kind of soft from the factory. As noted, many people go much bigger, but unless you autocross I'm not sure there's a benefit. Antisway bars will control the body roll without making the ride overly stiff.
