Don't be so quick to give up on the car.

You are not likely to get as much $ for parts as you think and might have to sit on the car for a while. If the salvage yard is giving you $ 200 over scrap for a car with a bad engine, that would be considered a good deal in the general car market. ( The motor is generally the most valuable part of a car with the trans second. )

These motors are rod benders with expensive rods / pistons. If the motor survived overboost without bending a rod, the motor is worth fixing.

Cracking an otherwise good head / block from a one time slight overboost on a stock engine is nearly impossible. Head cracks come from thermal cycles / overheating more than anything else.

If you pushed a gasket between two cylinders, compression will be low enough that fuel does not ignite and just gets pushed out the exhaust. Do a compression test or at least use a IR heat gun to measure exhaust temps at each manifold port to get some idea what cylinders are not firing.

With the engine cold, pull the rad cap and run the engine, see if bubbles / or a geyser of coolant come from the system. If so, combustion gasses are making their way from the cylinders to the water jackets.

I suspect stock over boost control is set pretty low, any one have the specs and a idea how much boost turned up diesels are making?