Never messed with a ponti dash, but I did go from chevy to buick, I retained the factory cluster (no gauges). I got lucky that the buick and chevy used the same plastic connector for the back of the cluster (I didn't take the wiring for the donor dash either 😳 ).
The biggest thing is getting the dash to fit properly. If you've ever had any dash out of a g-body, you may have noticed the extra tabs along the bottom of the windshield. I had to bend some the chevy mounting tabs out of the way, and use different ones, which I had to pry outward for the buick dash. It took many test fits, until I got the dash to sit correct and level, without being wavy. I retained the chevy headlamp switch along with the dash mounted wiper switch, buick had a different light switch connector, and a stalk wiper switch. Ventilation system, 😳 , I omitted long before the dash swap, so I have no clue what would have been needed to make it work (btw I regret doing that, lol).
I worried about the wiring last, all I did, was find out which each wire did, by using a test lamp and turning on and off accessories (turns, highs, back lamps, fuel level, etc), and marked each function. Then I looked at the back of the Buick cluster and traced each path on the printed curcuit, marked each path. I then rearranged the wires in the connector to correspond with the buicks cluster. Lots of goofing around to make it look good, and work properly, but when there's nothing else available, you use what you have access to (I needed a dash, but couldn't find a chevy one in good shape). Hope that helps a little, lol.
