the V8 fan will be way back from the rad so you'll either need a shroud or the original setup for 55-57 that moved the rad back and added some sheet metal pieces in front of the rad as "shrouding",
seen here [and found in the assembly manual] - if you look at your inner fenders, there's a reinforcing plate with 3 holes in a triangle, that's where the core support moves to ....
this is a 56 panel w/ 350 and aftermarket plastic shroud ..... and
this is a 58 with a correct style shroud, but from a 60's car, slightly modified to fit because the car rad is slightly different dimensions - it'd work on the 56 as well if you can find one
Bill