I would think you need the engine and transmission to load the front leaf springs to get the proper rear axle angle and determine driveshaft length.
Hopefully someone with more experience than myself will pipe-in here.
Getting the drivetrain set up and installed is the "meat and potatoes".
Wheels and how they look are "icing on the cake".
Normally the cake eating comes last in a meal (project).
My wife says I need to learn how to "multitask"....so...
Currently 6 X 5.5 front and 5 X 4.5 rear
For consideration:
Adding wheel adapters is a touchy subject here (safety).
Convert front to disc brakes and use "FERD" bolt circle pattern discs.
To get around disc clearance issues, seek out Wheelsmith.
Smoothie or Vintage rims and center caps that say "Chevrolet".
Coker original look tires for "eye candy" but radials, hands down, perform better.
If down the road you want IFS, you can reuse the discs and wheels.
