Project Nemesis is a fan driven website for games that use the One-Roll Engine (like Nemesis, Wild Talents, Reign and Monsters) or Chaosium's Basic Roleplay System (BRP) (like Call of Cthulhu) and the Delta Green setting.
I have run a trial game pitting Space Marines against Orks. For the Orks I used the rules found on this site. I came up with the following stats for Space Marines using the REIGN system.
The stats below simulate the Space Marines as the Gods of War they are portrayed as in GW fiction. Ten of these can defeat dozens of enemies. For the tabletop version you should lower all stats and skills with 1d and all armor with 1AP.
Adeptus Astartes
Body 5d
Athletics 4d
Endurance 4d
Fight 5d + 1Ed
Parry 5d
Run 3d
Vigor 4d+ed
According to the fiction, the Space Marines are flat out superhuman. I'd raise Coordination to 6 and Body to 5+MD.
Also, Resilient in Wild Talents transfers Killing into Shock (which then heals normally) after combat, rather than instantly removes Shock. This might better simulate the SM's reputed healing talents.
Also, the stats are for a brother marine. Captains and Commanders should have Body and/or Coordination 6. Commanders would also have MDs in Strategy, Tactics, Bolters and Chainswords.
Your Resilient version is a good suggestion. I will use that one.
The AA have several implants that make them superhuman. Two hearts, an extra size liver, and super-efficient lungs for starters.
Thick bone structure, etc etc.
Super fast healing from killing damage?
Not so much. IMHO.
6d body yes , regeneration no.
Sucking up shock damage after a fight yes.
They are super hot rodded humans in very nice armor with one purpose in mind.
'Killing your heretical ass.'
True, no MD for stats in Reign, but as a special situation for this, I thought it might apply. Minimum 6d Body then, I should think.
I would think faster healing from killing damage would apply. At a minimum the Primarchs had it, as the fiction about Leman Russ taking a Chainsword through the heart.
ORE Science-Fiction 
