I'm afraid I can't help much from first-hand experience with that kit.
That said, the Einherjar - as "space dwarfs" - seem to be a little shorter, so that might be a "small" problem (forgive me!), but I'm betting things like head and weapon swaps can work pretty well: the arms aren't THAT much shorter, surely!
You can see from the comparison shot that the Einherjar are about a head or so shorter than other Death Fields factions, but things like heads, hands, weapons, and so on are pretty close to the same size. The arms seem reasonably longish and might swap as-is with little or no problems, and at worst transplanting weapons at the wrist or glove-cuff is probably do-able. Accessories like backpacks, collars, etc. ought to be fine as-is.
I think you can do it pretty easily, with at most a little creative surgery for the arms.