Altered Vin. How to figure the original VIn

Ok I am new to this forum but I can't really seem to find the answer in my search. A long time ago when I was young and dumb I altered the VIN on a car that I owned. There was no theft involved , just a dumb lazy teenager that did not know the ramifications of what he was doing.

Here is how it came to pass. I was a the proud legitimate owner of a daily driver 67 Dodge Dart GT. I was 17 or so at the time and I was hit by another car. completely his fault. This was back in about 1991. The insurance company told me to get estimates to fix the car. It needed a new quarter panel but was drive able. I went to one body shop and they made mention they had a car just like that in the back. There was another 1967 Dodge Dart GT with no motor. Identical car except for this car was a different color and was factory air. i bought it fot 100 dollars and towed it home. Long story short. instead of cutting that dart up my VIN wound up on that car along with every other part I could unbolt from my other 67.

I now know this was the most idiotic thinges I could have done. I did not keep the new cars Vin and transferred my original Vin and data card over. What I wanthink to do now is figure out the correct Vin for the chassis and register it correctly. My original dart is long gone now and all I have is this 67 dart with altered VIN. i am not looking for advise on how to cheet. I did that already. I want to do it right. I know value is permanently ruined but I plan on keeping it and eventually putting it back together.

ok flame suit is on
Thanks ahead of time .