1966 barracuda rear window regulator & door Assem?

All these parts are rights and left's. They don't interchange with each other.
I’ve been trying to research the 66 barracuda you’ve been helpful for others I have a few questions I was wondering if you could answer.
1 what’s all involved with removing the ignition cylinder?
2 what’s involved with replacing the heater core?
3 have you read any complications with swapping to aftermarket gauges?