It would be better to use as many of your original parts as possible since they fit your application. If the bellhousing on the new engine is from a car it will not work in a truck. Also, car engines use different mount locations so you will need to work that out. Otherwise it should be a drop in.
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