It is the opposite way - a regular W124 was used as a donor car, normally with a totalled front end. Next it was sent an application to DMV to repair that car by replacing the front end + upgrading the car to 124036 spec's. The authorities hard stamped all parts to be replaced to keep full traceability and for final inspection of the build. The donor car had to be 10 years to avoid additional tax due to the increased engine displacement, power and weight.
Another way to come around the import tax, was to replace the entire chassis on a regular W124 + upgrading to 124036 spec's.
Both of these methods are now closed, but it is possible to apply for rebuilding cars on a general basis. Too much details to bring in about this, but the tax savings was huge, and I mean HUGE! ☺