I heard back from the owner of the car and SunDude has nailed it. The owner states the car was assembled in 1990-92, using the Bristol chassis and a C427 body from Classic Roadsters, and even mentioned the longer wheel base. He also stated he believes the chassis was an imported Bristol chassis and that is why the number is a BQX instead of the expected BEX, but "is not 100% sure". From what he wrote, it sounds like he was told this story when he bought it, but who knows for sure.
Jay