No, not exactly.
The early 168 teeth flywheels had a bolt pattern for a 10in clutch. The 10in clutch has now been replaced with a 10 1/2in (or if you prefer, 10.4in) clutch which used the SAME bolt pattern for the pressure plate. The FIRST Chevy V8 flywheels were ALLLLLLLLLLLLLL the 168 teeth version up through 1962. Then in 63, the smaller 153 teeth flywheel was introduced. Those flywheels ONLY USED the 10 1/2in clutch.
MOST of the early 168 teeth flywheels had the bolt pattern for a 10 or 10 1/2in clutch. BUUUUUUUUUUUUT, some of the early 168 teeth flywheels (police, taxi, HD, truck, etc) did have a bolt pattern for an 11in clutch.
Soooooooooooooo, here is where I'm going with all of this. Just because a flywheel is the 168 teeth version, IT MUST HAVE THE CORRECT BOLT PATTERN in order to use an 11in clutch!!! Beginning ABOUT 1962-63, MOST 168 teeth flywheels did have the bolt pattern for an 11in clutch.
Now, here is one more variation of the 168 teeth flywheel. SOME of them had a dual bolt pattern which permitted either an 11in or a 10 1/2in pressure plate to be bolted to the flywheel. But those were usually service replacement flywheels.
And, since the 12in clutch was mentioned, it also was used with the 168 teeth flywheel. BOTH 11in and 12in clutches used the same bolt pattern on a 168 teeth flywheel. FROM THE FACTORY, the only 12in clutches used in Chevrolets was truck applications, such as 1ton and larger. The 12in truck clutches required a different bell housing to accomodate the larger diameter of the 12in pressure plate.
There are AFTERMARKET 12in pressure plates that WILL FIT inside the stock pass car bell housing, such as the 621 housing.
Below is a 153 and 168 teeth flywheel. The 168 teeth flywheel has the bolt holes near the edge of the flywheel. This is the bolt pattern necessary for an 11in clutch (or 12in).
Here is one of the early 168 teeth flywheels. Notice the bolt pattern for the pressure plate. This flywheel will ONLY ACCEPT a pressure plate for a 10 1/2in clutch.