Depends on whether it's front or rear, and whether the vehicle is built for the U.S. market or Canadian market. For U.S. models, the rear wheel cylinder bore is 15/16" For Canadian models, the rear wheel cylinder bore is 1" and the front is 1-3/16" No data on the U.S. models front size ... although from looking at pictures it appears to be about 1" (and certainly would be expected to be at least 15/16", since the rears are 15/16". The fronts are generally larger than the rears, though).
389 and a 421 engine for a 1967 Pontiac catalina
I believe that is ( 20 U.S. gallons ) in a 1977 Pontiac Catalina
17 inch
P225/60r16
Most 1968 1969 Catalinas wear 235/70 R15 tires. Redlines I hope
6 cylinder - 4.3 4 cylinder - 2.2
Probably 14"
That will mount fine on a 7" wheel...but and 8 would be better.
I'm fairly certain it's a 30mm.
The exact Gap size is .045 I have the same car :^)
Check out: http://classiccardatabase.com/ Look up Pontiac 1955 then select your model or for the Chieftain and scan the data under tire/wheel size. Good luck! 55 Poncho Guy
Stock tire and wheel size was 6.95 x 14. http://www.automobile-catalog.com/tire/1965/829520/ford_mustang_hardtop_six.html