48 Dodge truck restore

Your first consideration is what do you want/expect the truck to be when you get finished.
Certainly using the stock chassis will be cheaper and easier than any other choice. But will it accomplish what you want?
Changing out the rear is pretty basic and retaining duel wheels is not a big deal although keeping the originals MIGHT be.

Changing the front over to a truck independent/type suspension can be a challenge but doable just the same. Bear in mind that keeping like wheels fore and aft needs to be a part of the choosing of donor parts. as well as track width.

Most every part you want is available for the engine and chassis including the brakes. But if you want to change gears the original parts may not allow for that. The straight axle will never drive like anything late model, or feel safe at common speeds of today.
but the brakes won't be OK at those speeds either. But if you keep the stock flat head six you won't have to worry about going that fast.

The parts that are not available are body/interior parts.
Changing the complete chassis over to a later model one will require the use of a tape measure and an open mind, particularly the possibility of relocating the engine to fit in the tight compartment you have to work with, and wheelbase/track width.
Of course you'll have to build body mounts and a plethora of other details.
There is far to much to cover it all here but I hope this gives you an idea of where you're going and how to get there.
Good luck with your project.. enjoy the journey.