One of my recent purchases was a set of Mark V (Heresy Armour) from Forge World. I figured that if I was gaming in the Horus Heresy era, then some (so called) Heresy era armour would be good to have as part of my Alpha Legion forces.
Below is an image of the boxed set bits all laid out.
All the bolts going through those ceramic layers are really iconic for this era. And those helmets are something else entirely. All together, I'm somewhat worried they might look a bit too Slaaneshi (so to speak), but I think they'll also look like they've always belonged in my Alpha Legion forces.