The 1 3/4" shoes are correct for 51-57 trucks. The backing plates were changed in 58 to use the 2" shoes which carried through the 60's. I would stay with the correct shoes for your year.
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