Looking at the pictures so far, he seems about twice the height of a standard marine, so a little shorter than a Contemptor. Have a look at the Dark Angels Contemptor towards the bottom of this page:
https://www.warhammer-community.com/2017/03/07/all-good-in-the-hood-eddies-fallen-angels/ - I think it makes good use of available parts. There's some obvious stuff from the Dark Angels Veteran sprue, the obligatory White Lion Chariot head, and I believe the banner is from the Empire Flagellants.