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You can look at the spec sheet for the ne5534.
There should be application notes, which give suggestions as to how this IC can best be utilized.
Then look at the compensation requirements (and in and output impedance requirements) of whatever discrete you'd like to try.
If you're thinking 99V, Joe at JLM is a great guy, very helpful.
Then look at your Presonus whatever and see if you can tell what parts of that circuit resemble one of the 5534 app notes.
People have said here that Presonus is very helpful about this stuff as well.
If you had to change other parts to drop in the opa627, those are probably a good place to start investigation. If you didn't, opa627 probably has its own app notes, like ne5534. You might want to compare the two. It has been mentioned here that ne5534 is not as 'picky' about it's requirements in a given circuit as some other opamps. Others may exhibit strange/unpleasing behavior when fitted within the same circuit.
You might be able to wire a discrete to the ne5534 dip spot, and use a board or mount to hold the discrete off the Presonus board.
From a fellow rookie, i'd say it will take some thought and plenty of research to get the best results from this.
