The thought of Shivan-looking weaponry on GTVA specs when they already have the clear advantage of strafing...

No way. I kinda get a rough idea of what's being suggested but were it up to me I'd still "leave it up to the modder". With those kinds of weapons anyone of moderate skill who constantly complains of the Shivans being too easy would immediately shut up after dying 3 seconds into a mission 20 times in a row, eating a blast from a Dragon firing five Shivanised Kayer shots or similar somesuch (this is greatly exaggerated but you get the idea).
I tried this kind of stuff long ago in a mod that was really a random test playground, similar case, "the Shivan weapons need to look believable from the player point of view" - even on Medium, godmode was practically essential to even start doing anything in the test mission. Though admittedly I didn't do direct copy paste; more towards new "actual" Shivan weapons with specs that put them in direct competition with, or even straight-up superior to GTVA weapons.

The other thing I'm more concerned about with things like this is with mods that use the MediaVPs. That's even more extra entries right there that some mods depending on plot might not even use despite needing MediaVPs for whatever reason. I get the idea with "Shivanising" the missiles (doesn't work for bombs because of the name shown on the target camera e.g. wouldn't Helios#Shivan still show as Helios?), but not so on guns because of balance really.
pls correct me if im wrong in any way, still not 100% sure on how the exe reads the data.