I've rewired 3 vehicles, all as modern updates. My 55 bird with a Centech panel and kit, the other two OT cars, with American Autowire. Both good, and there are others that are good.
I'm another (retired) sparky. The basic wiring is easy and straightforward, with the instructions.
On the 'bird, I did the dash on the bench. MSD ignition, p/w, p/seat, dual electric fans, elec fuel pump, a/c compressor. Aftermarket radio with 4 speakers, sub roofer, etc. Many more circuits than stock. Fuse links on primary feeds, where circuit breakers weren't convenient.
Bulkhead and multiple wire plugs, to tie the harnesses together.
All my crimps are with a pop off style tool, and you change dies as required. I use a modern, fire rated loom, that looks "old time". Lots of shrink sleeves for strain relief and on the loom. Careful soldering on things like the parking/headlights, where corrosion can be a problem.
Most of this is overkill, but if you do, or guarantee your work, it takes a ton of time. So different time estimates can reflect more just "wiring".
I'd encourage you to buy a good kit, with the wires attached to the fuse block (the Centech doesn't do this). Buy grommets for the firewall, stock or hot rod as you prefer, and a good crimper, not the cheap ones in the homeowner tool kit. And a good wire stripper.
The American Autowire kits came with more options, wiring diagrams, terminals, etc. than I needed. No big deal to me, I had all that stuff. And they had good parts, not cheap stuff that split when crimped.
When you hook it up, buy an inline fuse, and hook it up to the battery. Turn on one thing at a time. You'd rather blow a 20 amp fuse than melt down a new harness, or start a fire. When everything works, hook it up, and start the car.
One nice thing about doing it right, and yourself, it won't ever fail, and if it does, you can fix it.
So, as to what it should cost, what do you expect? All the above answers could be correct.