The Death Guard banner isn't necessarily pre-Heresy. I used this symbol because I didn't like the pre-heresy one.
The inspiration for the White Scars banners is from combining elements of various Scars heraldry that were in one of the Forge World Books.
My attempt at creating banners for 18 of the 20 first founding space marine chapters. Inspired by Warhammer 40k artwork from Games Workshop & Forge World Books, Games & Transfer Sheets as well as works from Baka-Design and 40-Kun.
If you like to see larger versions of the individual banners...