Turn signal switch won't be a problem. You will have to clip off the column connector (if your kit has one) but if you are using the original column you would do that anyway.
Headlight relays shouldn't be necessary with a new harness, but that is also easy to do (just run the headlight feed from the new harness into the coil pin on the relay).
The ammeter should be pretty simple, but without a wiring diagram in front of me I can't tell you exactly what to connect where.
I am not familiar enough with the generator control wiring to say how to do that. I would ping Hot Rod Lincoln as a local expert on generators and voltage regulators.
Jegs has a nice writeup with diagram for a few charging circuits:
https://answers.jegs.com/blog/10405...-for-universal-20-circuit-wiring-harness
