How hard is a rewire of a 61 with a universal harness?

[61Chevy454]

My truck needs a rewiring desperately, and I mean front to back. The last owner butchered my harness. I'm fairly certain I'm going to be buying the Speedway Economy 12 circuit harness, as it's far cheaper than all the other harness, and the quality is apparently on par, and I've even seen that it's better. Has anyone used the harness in question?

I'm also going to buy a new 5 gauge dash panel and a set of electric gauges from Omega, as I figure there will be a lot easier to wire up than the original gauge panel? It also has an electrical speedo sender so I can adjust my speedo so that it matches my bigger tire size, I reckon?

It's a stepside so I figure the brake light wiring will be easier than it would on a fleetside?

How difficult is this undertaking for someone who has barely wired anything?

Is it doable?