Pre heresy marines are defined by their legion (color and signs) and their older wargear.
While color is no problem the big problem comes with the wargear.
Even turning chaos marines into post heresy loyalists would require the removal of every chaos sign and most of the additional armor decorations. This is doable but would require a lot of additional work. On top of that most chaos helmets come with horns and spikes or other details that aren't in line with loyalists and would need a replacement.
If you want to actually recreate the armor of pre heresy models most of the parts - even after removal of decorations - would not fit.
So if you want a correct representation of the wargear of that aera while only using chaos marines ... you'd have to scratchbuild a lot of parts.
If you look at those tips and tutorials here:
http://www.mywargame.com/pre-heresy-model-and-painting-resources/ you'll notice that even with using all of
GW models (non forgeworld ones) you'll have lot of work to create pre heresy stuff with accurate wargear.
If you do not want to have a 100% accurate representation then just paint your models in legion colors and go with emperors children. As those are in my opinion the chapter that would fit best with highly decorated armor. But you'd still need to remove the eight pointed star of chaos, the eye of horus and probably some if not all of those arrows.
And you need new helmets.