You might also contact the folks at www.kustomrama.com for more info, they are based in Scandinavia and probably have some knowledge about the car. Very cool btw!!
The taillight bezels are very unique since they were cast from plastic resin then plasti- chromed, similar to the chrome plating found on model car parts and muscle car era dash inserts.
Petri is a super profilic builder and builts all of his customs in a one car residental garage by himself. He told me that when the roof was chopped, he actually hammered the form to it, not adding any welding, except the cutting seams. I painted the pinstripes and the picture in the rear deck. Besides this custom he has built some late forties Cadillac fastback, a super clean Buick 3W coupe and a Cad convertible. All with immaculate taste.
These are the only construction pics that I have of the Buick. Some of them show the minimal roof relief cuts and quality metal forming performed by Petri.
The magazine is called V8 Magazine, issue 7/2009. Your car is displayed on centerfold. I took a shot of it, the logo of th mag on the left side.