At the expense of anything else, or just more of this?
More of this.
If it was
me making the recommendations, I'd say "prioritize sabotaging the guidance packages of smart munitions and antitank/air-to-air weapons, the safeties on weapon fuzes so that the weapons are more likely to explode if dropped or mishandled, and on introducing deniable bugs to the software for the navigation and communications systems."
I'd also suggest "deliberately manufacture the parts to sloppy tolerances and say 'sorry sir best we can do' so that they'll have to keep replacing, fiddling with, and exchanging parts and have more jets deadlined for maintenance or engine wear at any one time," but if they're not
already doing that then I am
very very disappointed in them. 
...
But I'm trying to speak in-character about people who probably don't know much about fighter jets beyond "what can they drop on my head" and a reasonable level of 20th century military history literacy. And who can't conveniently look things up, and are afraid to bring in a consultant who knows jet fighters because that person might be a Victorian spy or mole.
So I can't get as specific, and my image of what might get requested in-character is something like "Try to make sure their munitions are unreliable, unsafe, and either poorly guided or unguided as much of the time as you can. We can survive getting dumb-bombed by jets, I don't want us to bet on surviving getting smart-bombed."
Redundant; will already be done. Nothing to be done on your end, after all, so nobody needs to know.
Good. That's a relief.
Somebody asked where Victoria gets its gadgets if the NCR stops playing ball, and I jokingly commented that they start using a lot more 7.62x39 ammunition (the USSR's favorite, and the cartridge that spread across the world with their blessing). My follow-up was clarifying that Alexander would stop being coy about his puppets supplying one another and would just do it directly.
Yeah, I figured.
I mean, if they give you open aid against the Victorians, as described, their timetable basically accelerates to, "immediately," as disguising troop and materiel movements across the Rockies as something more innocent is not really within their abilities.
If they could get
one thing to us, I'd be asking them for heavy surface-to-air missiles (the kind the size of a telephone pole that can hit a plane ten miles overhead, not the kind you fire from the shoulder like a bazooka and usually have a ceiling of a mile or two).
I'd want to ask them if they can do that specific thing. If they don't think they can pull it off deniably, that's a pity. If they can, that would be
great and we can reasonably hope to get by with little more.
Anything else, we can
probably manufacture an acceptable version of ourselves, or have an acceptable substitute for (e.g. mass production of something like WWII unguided bazooka rockets is possible with a fairly limited level of technology, and those are more than enough to act as can-openers against a T-34 if no gun-carrying vehicles of our own are in position to deal with them).
And they're just going to fall in line? What a bunch of pushovers.
More of a run-over; it's hard to continue disputing who gets to run your state government, when you've been ground into street pizza under the treads of an advancing armored personnel carrier.
