re-wiring a 69 Dart

Hi,

I have a 69 Dart that I would like to totally re-wire. I'd also like to put in an aftermarket Gauge cluster. Most of the aftermarket clusters I see are for 70 and up Darts. Will that cluster still work in a 69? Also I see alot of aftermarket wiring harnesses for sale and was looking at the painless kit. 21 Circuit Customizable 1966-76 Mopar Chassis HarnessDetails | Painless Performance
Can anyone give me feedback on that kit?

I'd like to be able to put in an aftermarket radio, amp and some speakers, nothing crazy, just something decent.

Any help or advise is appreciated.
Thanks
Ken