How out of place would these guys look in their respective current era chapters?

To avoid confusion, let me supplement that question:

  1. I know these are ridiculously old sets of armor that would be considered relics in their own right in the current setting

  2. I know that these Horus heresy units are obviously no longer a thing in 40k. I’m only interested in the armor/weapons

  3. Though I may partially kitbash them to fit in better, I won’t be attempting to “proxy” them into any sort of battlefield role.

So many of these Horus heresy models are cool as hell, and I know the first founding chapters still have a decent amount of relics around from that era (maybe some others do too, I’m not sure). But I’m wondering if I could put some of these guys into a 40k collection under the pretense that they’re just firstborn wearing old armor? I might mix and match a few things here and there like backpacks and such. Would this make any sense?

Also, if anyone who knows more about HH notices certain symbols or armor pieces that would need to be removed (if they indicate a battlefield role in their own right), let me know! Thanks guys