The VM is not an optimal engine. But at least it has a few hp more than a 3B. Lack of power is a general issue on any diesel available in a BJ73 of that period.bummer about the motor are they really that bad ?
Stressing the underpowered engines on highways and excessive 'offroad sports' is what kills them (regardless of actual engine type) (Together with age and high mileage).
I heard of quite some VM examples here in Europe that work well when properly maintained and used within reasonable capability limits.
Your problem may be that your engine is said to be already kind of shot. But you never gave any details yet.
I wouldn't agree that a VM is not worth any repairs. It depends on effort vs effort for alternatives vs desires vs capabilities of the owner vs funds.
If it's only about the head gasket: Easy and worth it. If there really is a cracked head: Different story, but still doable.
I recommend to first investigate the engines condition and then consider options based on facts.
The vehicle itself apparently is well worth restoring.
Cheers Ralf