diode models

I've used the 1n4004 model in a simulation and would like to put in a more accurate representation
of the high voltage diode I use.

Where is good documentation on spice models, or is it a good time to start using gnucap
native models to enter data from a part datasheet?

If native is good to use, the http://gnucap.org/dokuwiki/doku.php?id=gnucap:manual:examples:nonlinear_devices_--_diodes
page does not go into it.  Is there more documentation on native model parameters?

If this is not commonly done, then I will work around it by a crude substitution of as many 1n4004 diodes as model the volt drop.
I wonder if that will give trouble calculating... will the volt drop spread evenly...probably yes since identical models.