When I did the 235 to 350 conversion on my 56 the only V-8 flywheel I could find at the time used a 10" clutch. It worked fine for several years. I subsequently changed to an 11" later when some other changes were made. I really didn't see any difference.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine