Arvus Flyrant Proxy

My buddy is super into Genestealer cult. I suggested taking Tyranid allies until he can eventually buy 60+ hybrids. The dude's sitting on a mountain of Nid models... I'd suspect one of everything short of a dimachaeron (he's got epic Hierophants and Harridans).

I suggested a Flyrrant, Hive Crone (for some air) 30 Termaguants, Tervigon and Zoanthrope (for more Psychic dice). I know he has all the models... but he's got a sickness... he wants to make count-as/proxies/conversions from Imperial miniatures.

His idea is an Arvus Lighter and a Vulture gun ship to represent the flying monstrous creatures, dreadknight to represent Tervigon, crappy militia to represent the termaguants. He's an amazing conversion guy, so there's no doubt he'll do a great job, but the proxying a winged hive tyrant with a vehicle on a flight stand doesn't seem right to me.

I am attempting to talk him out of it, but he feels that plain old Nids just don't stack up well with the the new Genestealer Cult models.

Wondering, what are people's thoughts? Is there a strong argument against his crazy plan?

generally speaking, if your opponent can look at the model and guess what it is supposed to be, it'll fly. Having a good back story really seems to help.

I'd tell him to go for it.

Modeling, painting, and conversions is half the hobby.

Sounds like a lot of work, but hey if he's up for it why not! I remember an old Dwarf where a fella had written in with his idea for Tzeentch Lizardmen. He had some really cool conversion ideas with the Lizardmen becoming more and more birdlike with each treacherous spawning, but then he went and made his own army list by hand picking units from both the Lizardmen and Realms of Chaos books. Dirty Steve replied that he should be taking rules from one codex or the other to keep things fair and I think as long as your friend does the same there should be no real problems, plus when he does want to run IG as allies he will have some sweet models!
I'm planning on doing something similar, not similar and give fluffy Tyranid names to my Guard Allies, stuff like naming my gunship the Sky Tyrant and loading them up with cult bling and symbols.
That is if I ever finish painting cultists, lol.

It's his army, after all. For the Termagents that's easy. Old style was to give some Cultists the odd Genestealer arm and a Bolt Pistol, because Fleshborers and Bolt Pistols are the exact same. A Devourer could be some sort of Combat Shotgun or Autogun, but up-gunned to heck.

The Fliers are trickier, I mean a vehicle doesn't really make much sense in terms of combat. It represents the flight, and the shooting fairly well, but if it gets shot down it won't make much sense when it gets back into the air again after crashing, and combat won't really make sense either. Nor will vector striking tbh, but I suppose he could have it carrying a payload of bombs to cover that.