First, what is the year/model of the car being tested?
Mileage on the car?
Maintence records?
Frequent oil changes?
These questions will help give better responses from people.

A diesel needs 300+psi to be "healthy."
255psi minimum to ignite Diesel.
There is no max. as far as I have ever seen.

Anything, to me, above 350psi on a small diesel is good.

I say you have very good compression. Take care of it.