What are the differences between a small and block and big block engine wiring harness for a 70's D100 truck?

I am aware that the big block is a little longer and things like senders might have a different location. That said, could I make a small block harness work on a big block or is it not worth the hassle?

The engine harness on my D100 has seen better days and has suffered a lot of amateur butchery. Rather than trying to refurbish the existing one with all the brittle connectors and corroded terminals, I figured I'd buy new. Just having a tough time locating a big block one for a reasonable price.

Not interested in rewiring the car with a universal kit or anything. The rest of the wiring is mostly OK, just the engine harness needs to be replaced.

Thanks for any input.

- Greg