Alright, here's the guide in completely unnecessary detail. Sorry for the number of pictures and their inconsistency.
In the end I decided to use heat lances for the guns this time, as seen in Daemonkin's
thread, but I've also mentioned how I did the first revenant's guns.
STUFF YOU'LL NEEDI got stuff from bits and kits, mainly when a sale was on. Other bits suppliers are of course available, but this is what I used:
If you want to use heat lances instead of cutting down the wraithguard guns, you'll want the heat lances. If you want the oversized holofield vane I've used you'll want the wraithlord fin, otherwise the wraithguard default one should be fine.
So here are the bits you'll definitely need highlighted in red, the optional fin in orange and the weapons to choose between in yellow: (of course you might choose a different loincloth or arms to these)
BODY AND LEGSThe body is pretty much the standard body from the wraithguard. So I'd have a bit more freedom with the posing of the legs, I clipped off the pegs from the hips and trimmed a bit away from the hips. I also clipped the dome off the neck piece so that I'd be able to fit on a dire avenger head. I attached the legs with some combination of brass rod and green stuff in a sort of floating position.
HOLOFIELD VANEI took the normal vane from the back of a wraithguard and the larger wraithlord one, cut them to fit and glued them. I wasn't careful enough so it's a tiny bit wonky, but it's not too noticeable.


I glued it in place on the back.
HEADI cut the neck of the dire avenger head so that it was straight and would fit nicely onto the neck plate.

I didn't want the crest, so I attacked it with clippers (this was a bit stupid, it could have gone wrong) and then cleaned up with a knife.
ARMS & WEAPONSI cut the guns where they'd be attached to the arms (top picture for using heat lances, bottom for wraithguard weapons).


For the wraitguard guns I then trimmed them down with clippers and a knife until they looked a bit like this:

It's a bit messy where the hands were, but you can either put some green stuff on or just be fairly clean with your cuts and not worry about it too much.
I cut the arms at the wrists so that there would be a flat surface to attach the guns to.

I then drilled holes in the wrists and the corresponding end of the guns so that they could be stuck together with help from brass rod.
JUMP PACKPretty much the last thing to do was the jump pack (apart from the loincloth thing, make sure your pose is compatible with the loincloth because it's really fragile if you try to bend it..).
I took the jump pack bits and trimmed the vent down so that it'd fit properly. I also shaved off the pegs from the "inside" of the jump pack bits, then glued on the vent parts.


There was a gap on the "inside", so I cut a piece of plasticard slightly bigger than the side of the jump pack and glued it to the open part (I think I used 0.5mm, it has to be bent to the shape of the jump pack so needs to be fairly thin). I trimmed it to shape and cut a semicircle by the semicircle on top of the jump pack piece. This leaves space for the neck plate.


I attached the jump pack to the revenant at the points marked in red - the cut out semicircle is attached to the neck plate and the bottom of the jump pack to the shoulder pad.
FINISHED!That's pretty much it, I'm going to pin one of the feet into a resin base to finish mine. Here are the almost finished versions with the different gun options.


And another picture of the painted one.

Hope that made some sense!