Here's the Durango in her (original?) Confed livery circa 2665. This version is the TCS Delphi, DD-47 the original incarnation of the BWS Intrepid before she was sold to the UBW and rechristened CVL-06.
Oooh, very nice idea to do a Confed paintjob. Your style is obviously not quite the same as Eder's, but that ship certainly wouldn't look much out of place in Standoff! However, you may want to consider some kind of structural changes. We obviously don't know what the Durangoes looked like originally, and they may well have been exactly the same as the carrier variant. But logically, we wouldn't expect them to be, just as we wouldn't expect Wake-class CVEs to look exactly the same as the hejavy transport from which the design originates.
I'm not really sure what
should be different to make a convincing heavy destroyer out of the above. Use your imagination, though. Maybe close off the forward hangar, so that there is only a (significantly smaller) rear hangar? We often see hangars on destroyers and cruisers in WC, but through-deck hangars seem to only show up on carriers. You could then add some forward-facing heavy armaments in the place of the forward hangar. Something that would look like a bunch of AMGs, for instance, to indicate that the "heavy" part of the designation doesn't only mean size and mass, but also heavier armament. And the fact that it would be forward-facing would also explain why the ship was eventually converted into a carrier and those guns removed - after all, by the time of WC3/4, we see heavy weaponry only in turreted form.
Whatever you do, I'm sure the Homeworld mod team will be happy, because units built by conversion from other units are always a neat thing in RTS games