1969 barracuda V-8 complete wiring overhaul. Best kit? Tips?

What is your goal?

If you want it all stock. M&H is the best way to go. Year One or (Classic Industries Maybe)

M&H does not have the accessory harness under the dash just the main harness. They also do not have the console and passenger side c-pillar dome harness. They can make them though.

If you just want to make one then there are lots of options.

Painless
Ron Francis
and sure plenty more.