If I was going to re-wire a car I would have to look at it and discuss it with you.

Some important things to look at are.

1. Do you want all new wiring or fix, repair, and upgrade existing wiring. Replacing wiring can go two ways. All new harnesses or build them from scratch. Building them from scratch is not what I suggest for a car with readily available harnesses. Too many connectors, sockets, wrapping etc needs to be included plus the myriad of colored wiring to make it professional. I would only suggest building a harness in specialty applications. Racecar, streetrod, kitcar, or cars with no available harnesses like a 60's rambler.

2. If you want a fix, repair, and upgrade to existing wiring what does the current wiring look like? The whole harness needs to be inspected and the dash/engine harnesses unwrapped to inspect it right. Rat's nest repairs, cut chaffed wires, etc need to be removed and repaired correctly. Solder only no crimps, bulkhead terminals replaced but how are the bulkhead connectors?

3. What kind of upgrades? Halogen lights on relay's? 100,000 giga-what ear bleed stereo? Alarm system? Electronic engine like a stock modern Hemi? Battery cutout? electronic ignition? LED lights (Dash, marker & Taillights)? Foot dimmer switch, Door switches, etc are they good/bad? Do you want to replace (Save trouble later) or just check (Save money now)?
I have had good outcomes with old Mopars by rebuilding the harnesses and adding upgrades to the main power circuits.
a. Fusible links at the Alternator & Starter relay connections,
b. straight wire or bulkhead bypass for the two main power wires from dash to engine compartment,
c. bumping the main power wires to 10 gage,
d. soldering the power wires to the ignition switch instead of using the under dash connector.
e. Replacing the terminals in the bulkhead connector, headlight, wiper, & heater switches.

Good fuse blocks are the sticking point on our old cars. Often a harness is needed to repair bad fuse blocks. They are integrated into the harness. it's more than the plastic block that often gets charred. You need to replace the terminals in the block which is a problem. They are sorta integral to the harness.

Also consider replacing the fan motor for the heat/AC. They often are old and pull so much current they overload the switches & fuses.

If you are replacing switches what kind of quality? Cheap china switches or expensive NOS/OEM switches?

Depending on how you want it done it could be hundreds or thousands.

If you have time and another daily driver it's not a bad time to learn wiring.