I once had a pretty good 261 in a 1953 210 and a heavy duty 9" clutch was fine. What was a problem were the bushings on the countershaft of the '53 transmission. After wearing down two sets in a few thousand miles I replaced the 1953 transmission with a 1954 transmission with needle bearings. These never went bad. I also had similar experience with a 1951 Chevy with a 261. I bought a Schiefer 10" aluminum flywheel and clutch for it when I converted to an open drive shaft with a Muncie 4-speed and a truck bellhousing.
There were 10" and 10-3/4" clutches for the 1954 and earlier trucks. I'm not sure if these will fit in a passenger car bell housing.
