Ok, where do I begin?

I've got an 86 third gen, had an original 305 tpi, trying to put in an 89, 305, tpi engine. Yes. A 305. LOL

Anyway, after realizing the wiring was completely different, I have obtained a new harness and computer.

One problem I see so far, the harness injector wires aren't marked. Now, common sense tells me which side of the engine they go on, but after that, I have no clue. Is there a way to figure this out without a trial and error process?

I read one post saying it didn't matter. Is that true?

Any help is appreciated. Thanks.